mac80211: fix txq queue related crashes

mac80211: fix txq queue related crashes

Orabug: 25308062

[ Upstream commit 2a58d42c1e018ad514d4e23fd33fb2ded95d3ee6 ]

The driver can access the queue simultanously
while mac80211 tears down the interface. Without
spinlock protection this could lead to corrupting
sk_buff_head and subsequently to an invalid
pointer dereference.

Fixes: ba8c3d6f16a1 ("mac80211: add an intermediate software queue implementation")
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
(cherry picked from commit 17e8cd1e540985cd11cc6f007867fa1679b8f866)
Signed-off-by: Dhaval Giani <dhaval.giani@oracle.com>