wifi: mac80211: check key taint for beacon protection

This will likely never happen, but for completeness check
the key taint flag before using a key for beacon protection.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230301115906.cf2c3fee6f1f.I2f19b3e04e31c99bed3c9dc71935bf513b2cd177@changeid


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