nl80211/mac80211: Perform PLINK_ACTION on new station

Modify the NEW_STATION command to accept PLINK_ACTIONS, in case
userspace wants to create stations and initiate a peer link right away
(for authenticated stations) or create a blocked station (for
debugging).

Signed-off-by: Javier Cardona <javier@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>