mac80211: add basic support for WoWLAN

This adds basic support for the new WoWLAN
configuration in mac80211. The behaviour is
completely offloaded to the driver though,
with two new callbacks (suspend/resume).

Options for the driver include a complete
reconfiguration after wakeup, and exposing
all the triggers it wants to support.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>