Remove superfluous va_end which was left there in rev 1.38.

Approved by: kib (mentor)

bin/rcp/rcp.c

@@ -789,6 +789,4 @@ run_err(const char *fmt, ...)
 		vwarnx(fmt, ap);
 		va_end(ap);
 	}
-
-	va_end(ap);
 }