Fix regression from r353026. Pointer was increased instead of value

pointed to.

PR:		241646
Submitted by:	Aleksandr Fedorov <aleksandr.fedorov itglobal.com>

sys/netgraph/ng_bridge.c

@@ -977,7 +977,7 @@ ng_bridge_unmute(hook_p hook, void *arg)
 			    ng_bridge_nodename(node), NG_HOOK_NAME(hook));
 		}
 	}
-	counter++;
+	(*counter)++;
 	return (1);
 }