iavf: Fix a crash during reset task

Recent commit aa626da9 ("iavf: Detach device during reset task")
removed netif_tx_stop_all_queues() with an assumption that Tx queues
are already stopped by netif_device_detach() in the beginning of
reset task. This assumption is incorrect because during reset
task a potential link event can start Tx queues again.
Revert this change to fix this issue.

Reproducer:
1. Run some Tx traffic (e.g. iperf3) over iavf interface
2. Switch MTU of this interface in a loop

[root@host ~]# cat repro.sh

IF=enp2s0f0v0

iperf3 -c 192.168.0.1 -t 600 --logfile /dev/null &
sleep 2

while :; do
        for i in 1280 1500 2000 900 ; do
                ip link set $IF mtu $i
                sleep 2
        done
done
[root@host ~]# ./repro.sh

Result:
[  306.199917] iavf 0000:02:02.0 enp2s0f0v0: NIC Link is Up Speed is 40 Gbps Full Duplex
[  308.205944] iavf 0000:02:02.0 enp2s0f0v0: NIC Link is Up Speed is 40 Gbps Full Duplex
[  310.103223] BUG: kernel NULL pointer dereference, address: 0000000000000008
[  310.110179] #PF: supervisor write access in kernel mode
[  310.115396] #PF: error_code(0x0002) - not-present page
[  310.120526] PGD 0 P4D 0
[  310.123057] Oops: 0002 [#1] PREEMPT SMP NOPTI
[  310.127408] CPU: 24 PID: 183 Comm: kworker/u64:9 Kdump: loaded Not tainted 6.1.0-rc3+ #2
[  310.135485] Hardware name: Abacus electric, s.r.o. - servis@abacus.cz Super Server/H12SSW-iN, BIOS 2.4 04/13/2022
[  310.145728] Workqueue: iavf iavf_reset_task [iavf]
[  310.150520] RIP: 0010:iavf_xmit_frame_ring+0xd1/0xf70 [iavf]
[  310.156180] Code: d0 0f 86 da 00 00 00 83 e8 01 0f b7 fa 29 f8 01 c8 39 c6 0f 8f a0 08 00 00 48 8b 45 20 48 8d 14 92 bf 01 00 00 00 4c 8d 3c d0 <49> 89 5f 08 8b 43 70 66 41 89 7f 14 41 89 47 10 f6 83 82 00 00 00
[  310.174918] RSP: 0018:ffffbb5f0082caa0 EFLAGS: 00010293
[  310.180137] RAX: 0000000000000000 RBX: ffff92345471a6e8 RCX: 0000000000000200
[  310.187259] RDX: 0000000000000000 RSI: 000000000000000d RDI: 0000000000000001
[  310.194385] RBP: ffff92341d249000 R08: ffff92434987fcac R09: 0000000000000001
[  310.201509] R10: 0000000011f683b9 R11: 0000000011f50641 R12: 0000000000000008
[  310.208631] R13: ffff923447500000 R14: 0000000000000000 R15: 0000000000000000
[  310.215756] FS:  0000000000000000(0000) GS:ffff92434ee00000(0000) knlGS:0000000000000000
[  310.223835] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  310.229572] CR2: 0000000000000008 CR3: 0000000fbc210004 CR4: 0000000000770ee0
[  310.236696] PKRU: 55555554
[  310.239399] Call Trace:
[  310.241844]  <IRQ>
[  310.243855]  ? dst_alloc+0x5b/0xb0
[  310.247260]  dev_hard_start_xmit+0x9e/0x1f0
[  310.251439]  sch_direct_xmit+0xa0/0x370
[  310.255276]  __qdisc_run+0x13e/0x580
[  310.258848]  __dev_queue_xmit+0x431/0xd00
[  310.262851]  ? selinux_ip_postroute+0x147/0x3f0
[  310.267377]  ip_finish_output2+0x26c/0x540

Fixes: aa626da9 ("iavf: Detach device during reset task")
Cc: Jacob Keller <jacob.e.keller@intel.com>
Cc: Patryk Piotrowski <patryk.piotrowski@intel.com>
Cc: SlawomirX Laba <slawomirx.laba@intel.com>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/iavf/iavf_main.c

@@ -3033,6 +3033,7 @@ static void iavf_reset_task(struct work_struct *work)
 
 	if (running) {
 		netif_carrier_off(netdev);
+		netif_tx_stop_all_queues(netdev);
 		adapter->link_up = false;
 		iavf_napi_disable_all(adapter);
 	}