xfs: fix duplicate message output

Commit 957935dc ("xfs: fix xfs_debug warnings" broke the logic in
__xfs_printk(). Instead of only printing one of two possible output
strings based on whether the fs has a name or not, it outputs both.
Fix it to only output one message again.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

fs/xfs/linux-2.6/xfs_message.c

@@ -34,8 +34,10 @@ __xfs_printk(
 	const struct xfs_mount	*mp,
 	struct va_format	*vaf)
 {
-	if (mp && mp->m_fsname)
+	if (mp && mp->m_fsname) {
 		printk("%sXFS (%s): %pV\n", level, mp->m_fsname, vaf);
+		return;
+	}
 	printk("%sXFS: %pV\n", level, vaf);
 }