Otherwise, we might call the driver callback before
the interface was uploaded.

Solves the following warning:
WARNING: at net/mac80211/driver-ops.h:12 ieee80211_set_bitrate_mask+0xbc/0x18c [mac80211]()
wlan0:  Failed check-sdata-in-driver check, flags: 0x0
Modules linked in: wlcore_sdio wl12xx wl18xx wlcore mac80211 cfg80211 [last unloaded: cfg80211]
[<c001b964>] (unwind_backtrace+0x0/0x12c) from [<c0495550>] (dump_stack+0x20/0x24)
[<c0495550>] (dump_stack+0x20/0x24) from [<c003ee28>] (warn_slowpath_common+0x5c/0x74)
[<c003ee28>] (warn_slowpath_common+0x5c/0x74) from [<c003eefc>] (warn_slowpath_fmt+0x40/0x48)
[<c003eefc>] (warn_slowpath_fmt+0x40/0x48) from [<bf5c1ad0>] (ieee80211_set_bitrate_mask+0xbc/0x18c [mac80211])
[<bf5c1ad0>] (ieee80211_set_bitrate_mask+0xbc/0x18c [mac80211]) from [<bf575960>] (nl80211_set_tx_bitrate_mask+0x350/0x358 [cfg80211])
[<bf575960>] (nl80211_set_tx_bitrate_mask+0x350/0x358 [cfg80211]) from [<c03e9e94>] (genl_rcv_msg+0x1a8/0x1e8)
[<c03e9e94>] (genl_rcv_msg+0x1a8/0x1e8) from [<c03e9164>] (netlink_rcv_skb+0x5c/0xc0)
[<c03e9164>] (netlink_rcv_skb+0x5c/0xc0) from [<c03e9ce0>] (genl_rcv+0x28/0x34)
[<c03e9ce0>] (genl_rcv+0x28/0x34) from [<c03e8e74>] (netlink_unicast+0x158/0x234)
[<c03e8e74>] (netlink_unicast+0x158/0x234) from [<c03e93e0>] (netlink_sendmsg+0x218/0x298)
[<c03e93e0>] (netlink_sendmsg+0x218/0x298) from [<c03b4e5c>] (sock_sendmsg+0xa4/0xc0)
[<c03b4e5c>] (sock_sendmsg+0xa4/0xc0) from [<c03b5af4>] (__sys_sendmsg+0x1d8/0x254)
[<c03b5af4>] (__sys_sendmsg+0x1d8/0x254) from [<c03b5ca8>] (sys_sendmsg+0x4c/0x70)
[<c03b5ca8>] (sys_sendmsg+0x4c/0x70) from [<c0013980>] (ret_fast_syscall+0x0/0x3c)

Note that calling the driver can also result
in undefined behaviour since it doesn't have
to deal with calls while down.
Signed-off-by: Eliad Peller <eliad@wizery.com>
[removed timestamps, added note - Johannes]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>