wl1271: Mask unneeded events from firmware to conserve power

Currently several events are enabled from the firmware for which there
is no handling. This wakes up the host unnecessarily. Mask those
unneeded events.

Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Reviewed-by: Luciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: Luciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>