xfs/276: remove unnecessary mkfs golden output

A previous update to this test dropped the clause where the mkfs
standard output gets sent to /dev/null.  The filtered mkfs output isn't
needed here and it breaks the test, so fix that.

Fixes: e97f96e5 ("xfs/27[26]: force realtime on or off as needed")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>
diff --git a/tests/xfs/276 b/tests/xfs/276
index 6e2b2fb..afea48a 100755
--- a/tests/xfs/276
+++ b/tests/xfs/276
@@ -35,7 +35,7 @@
 rm -f "$seqres.full"
 echo "Format and mount"
-_scratch_mkfs | _filter_mkfs 2> "$tmp.mkfs"
+_scratch_mkfs | _filter_mkfs 2> "$tmp.mkfs" >/dev/null
 . $tmp.mkfs
 cat "$tmp.mkfs" > $seqres.full