This patch enables raw Rx/Tx encap mode to support software based
crypto engine. This patch introduces a new module param 'cryptmode'.

 cryptmode:

   0: Use hardware crypto engine globally with native Wi-Fi mode TX/RX
      encapsulation to the firmware. This is the default mode.
   1: Use sofware crypto engine globally with raw mode TX/RX
      encapsulation to the firmware.

Known limitation:
   A-MSDU must be disabled for RAW Tx encap mode to perform well when
   heavy traffic is applied.

Testing: (by Michal Kazior <michal.kazior@tieto.com>)

     a) Performance Testing

      cryptmode=1
       ap=qca988x sta=killer1525
        killer1525  ->  qca988x     194.496 mbps [tcp1 ip4]
        killer1525  ->  qca988x     238.309 mbps [tcp5 ip4]
        killer1525  ->  qca988x     266.958 mbps [udp1 ip4]
        killer1525  ->  qca988x     477.468 mbps [udp5 ip4]
        qca988x     ->  killer1525  301.378 mbps [tcp1 ip4]
        qca988x     ->  killer1525  297.949 mbps [tcp5 ip4]
        qca988x     ->  killer1525  331.351 mbps [udp1 ip4]
        qca988x     ->  killer1525  371.528 mbps [udp5 ip4]
       ap=killer1525 sta=qca988x
        qca988x     ->  killer1525  331.447 mbps [tcp1 ip4]
        qca988x     ->  killer1525  328.783 mbps [tcp5 ip4]
        qca988x     ->  killer1525  375.309 mbps [udp1 ip4]
        qca988x     ->  killer1525  403.379 mbps [udp5 ip4]
        killer1525  ->  qca988x     203.689 mbps [tcp1 ip4]
        killer1525  ->  qca988x     222.339 mbps [tcp5 ip4]
        killer1525  ->  qca988x     264.199 mbps [udp1 ip4]
        killer1525  ->  qca988x     479.371 mbps [udp5 ip4]

      Note:
       - only open network tested for RAW vs nwifi performance comparison
       - killer1525 (qca6174 hw2.2) is 2x2 device (hence max 866mbps)
       - used iperf
       - OTA, devices a few cm apart from each other, no shielding
       - tcpX/udpX, X - means number of threads used

      Overview:
       - relative Tx performance drop is seen but is within reasonable and
         expected threshold (A-MSDU must be disabled with RAW Tx)

     b) Connectivity Testing

      cryptmode=1
       ap=iwl6205 sta1=qca988x crypto=open     topology-1ap1sta          OK
       ap=iwl6205 sta1=qca988x crypto=wep1     topology-1ap1sta          OK
       ap=iwl6205 sta1=qca988x crypto=wpa      topology-1ap1sta          OK
       ap=iwl6205 sta1=qca988x crypto=wpa-ccmp topology-1ap1sta          OK
       ap=qca988x sta1=iwl6205 crypto=open     topology-1ap1sta          OK
       ap=qca988x sta1=iwl6205 crypto=wep1     topology-1ap1sta          OK
       ap=qca988x sta1=iwl6205 crypto=wpa      topology-1ap1sta          OK
       ap=qca988x sta1=iwl6205 crypto=wpa-ccmp topology-1ap1sta          OK
       ap=iwl6205 sta1=qca988x crypto=open     topology-1ap1sta2br       OK
       ap=iwl6205 sta1=qca988x crypto=wep1     topology-1ap1sta2br       OK
       ap=iwl6205 sta1=qca988x crypto=wpa      topology-1ap1sta2br       OK
       ap=iwl6205 sta1=qca988x crypto=wpa-ccmp topology-1ap1sta2br       OK
       ap=qca988x sta1=iwl6205 crypto=open     topology-1ap1sta2br       OK
       ap=qca988x sta1=iwl6205 crypto=wep1     topology-1ap1sta2br       OK
       ap=qca988x sta1=iwl6205 crypto=wpa      topology-1ap1sta2br       OK
       ap=qca988x sta1=iwl6205 crypto=wpa-ccmp topology-1ap1sta2br       OK
       ap=iwl6205 sta1=qca988x crypto=open     topology-1ap1sta2br1vlan  OK
       ap=iwl6205 sta1=qca988x crypto=wep1     topology-1ap1sta2br1vlan  OK
       ap=iwl6205 sta1=qca988x crypto=wpa      topology-1ap1sta2br1vlan  OK
       ap=iwl6205 sta1=qca988x crypto=wpa-ccmp topology-1ap1sta2br1vlan  OK
       ap=qca988x sta1=iwl6205 crypto=open     topology-1ap1sta2br1vlan  OK
       ap=qca988x sta1=iwl6205 crypto=wep1     topology-1ap1sta2br1vlan  OK
       ap=qca988x sta1=iwl6205 crypto=wpa      topology-1ap1sta2br1vlan  OK
       ap=qca988x sta1=iwl6205 crypto=wpa-ccmp topology-1ap1sta2br1vlan  OK

      Note:
       - each test takes all possible endpoint pairs and pings
       - each pair-ping flushes arp table
       - ip6 is used

     c) Testbed Topology:

      1ap1sta:
        [ap] ---- [sta]

        endpoints: ap, sta

      1ap1sta2br:
        [veth0] [ap] ---- [sta] [veth2]
           |     |          |     |
        [veth1]  |          \   [veth3]
            \   /            \  /
            [br0]            [br1]

        endpoints: veth0, veth2, br0, br1
        note: STA works in 4addr mode, AP has wds_sta=1

      1ap1sta2br1vlan:
        [veth0] [ap] ---- [sta] [veth2]
           |     |          |     |
        [veth1]  |          \   [veth3]
            \   /            \  /
          [br0]              [br1]
            |                  |
          [vlan0_id2]        [vlan1_id2]

        endpoints: vlan0_id2, vlan1_id2
        note: STA works in 4addr mode, AP has wds_sta=1

Credits:

    Thanks to Michal Kazior <michal.kazior@tieto.com> who helped find the
    amsdu issue, contributed a workaround (already squashed into this
    patch), and contributed the throughput and connectivity tests results.
Signed-off-by: David Liu <cfliu.tw@gmail.com>
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Tested-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>