S390/sysinfo: use uuid_is_null instead of opencoding it

And switch to use uuid_t instead of the old uuid_be type.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

arch/s390/kernel/sysinfo.c

@@ -242,7 +242,7 @@ static void print_ext_name(struct seq_file *m, int lvl,
 
 static void print_uuid(struct seq_file *m, int i, struct sysinfo_3_2_2 *info)
 {
-	if (!memcmp(&info->vm[i].uuid, &NULL_UUID_BE, sizeof(uuid_be)))
+	if (uuid_is_null(&info->vm[i].uuid))
 		return;
 	seq_printf(m, "VM%02d UUID:            %pUb\n", i, &info->vm[i].uuid);
 }