iwlwifi: mvm: disconnect if time event scheduling fails

If scheduling an important time event fails, or if we get
an unexpected notification from the firmware, there isn't
much we can do to recover, so just drop the connection and
let higher layers retry it.

Reviewed-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>