FS-477 mod_skinny fix leaked lock

src/mod/endpoints/mod_skinny/mod_skinny.c

@@ -1682,7 +1682,6 @@ switch_status_t listener_digit_timeout(listener_t *listener)
 	if ( !session)
 		return SWITCH_STATUS_FALSE;
 
-
 	channel = switch_core_session_get_channel(session);
 	tech_pvt = switch_core_session_get_private(session);
 
@@ -1692,6 +1691,8 @@ switch_status_t listener_digit_timeout(listener_t *listener)
 		listener->digit_timeout_time = 0;
 	}
 
+	switch_core_session_rwunlock(session);
+
 	return SWITCH_STATUS_SUCCESS;
 }