All configuration sequences should be protected
with conf_mutex to avoid concurrent/conflicting
requests.

This should make sure that wep tx key setup is not
performed while hw is restarted (at least).
Signed-off-by: NMichal Kazior <michal.kazior@tieto.com>
Signed-off-by: NKalle Valo <kvalo@qca.qualcomm.com>