cfg80211: Acquire wiphy mutex on regulatory work

The function cfg80211_reg_can_beacon_relax() expects wiphy
mutex to be held when it is being called. However, when
reg_leave_invalid_chans() is called the mutex is not held.
Fix it by acquiring the lock before calling the function.

Fixes: a05829a7 ("cfg80211: avoid holding the RTNL when calling the driver")
Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20211202152831.527686cda037.I40ad9372a47cbad53b4aae7b5a6ccc0dc3fddf8b@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>