wl1251: fix NULL pointer dereference
Signed-off-by: NPali Rohár <pali.rohar@gmail.com>
Reported-by: NFelipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: NPavel Machek <pavel@ucw.cz>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>