iwlwifi: unregister LEDs if mac80211 registration fails

commit 0e1fa7ef25004b9c1a14147bce61c15c2f1c6744 upstream.

Otherwise the LEDs stick around and cause issues the
next time around since they're still there but not
really hooked up.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>