mac80211: Allow single vif mac address change with addr_mask

When changing the MAC address of a single vif mac80211 will check if
the new address fits into the address mask specified by the driver.
This only needs to be done when using multiple BSSIDs. Hence, check
the new address only against all other vifs.

Also fix the MAC address assignment on new interfaces if the user
changed the address of a vif such that perm_addr is not covered by
addr_mask anymore.

Resolves:
https://bugzilla.kernel.org/show_bug.cgi?id=57371



Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: Jakub Kicinski <kubakici@wp.pl>
Reported-by: Alessandro Lannocca <alessandro.lannocca@gmail.com>
Cc: Alessandro Lannocca <alessandro.lannocca@gmail.com>
Cc: Bruno Randolf <br1@thinktube.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>