add missing unlock not present in 294277

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.6.2@294312 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_timing_timerfd.c

@@ -228,6 +228,7 @@ static int timerfd_timer_disable_continuous(int handle)
 		/* No reason to do anything if we're not
 		 * in continuous mode
 		 */
+		ao2_unlock(our_timer);
 		ao2_ref(our_timer, -1);
 		return 0;
 	}