libreboot-utils: replace rlong() with rset()

now you can send an arbitrary number of bytes
with random numbers

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/libreboot-utils/lib/num.c

@@ -84,7 +84,7 @@ hextonum(char ch_s)
 
 	if (ch == '?' || ch == 'x') {
 
-		rval = rlong();
+		rset(&rval, sizeof(rval));
 		if (errno > 0)
 			goto err_hextonum;