Add missing va_end() to clean up after va_start().

CID:		4725
Found with:	Coverity Prevent(tm)
MFC after:	1 week

sys/dev/ppbus/ppb_msq.c

@@ -244,6 +244,7 @@ ppb_MS_init_msq(struct ppb_microseq *msq, int nbparam, ...)
 		}
 	}
 
+	va_end(p_list);
 	return (0);
 }