wifi: mac80211: allow for_each_sta_active_link() under RCU

Since we only use this to protect the dereference and with
STA mutex, we can also allow this with just RCU.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230920211508.73c3e04985f4.I52ef396d693e0e381a73eade06850137d8900948@changeid


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