iwlwifi: do proper hw restart

When the microcode fails for any reason, ask mac80211 to
recover instead of trying ourselves and failing at it.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>