common/rc: relax xfs swapfile support checks

In commit 725feeff, I forgot that xfs has *not* always supported all
swap file configurations -- the bmap swapfile activation prior to the
introduction of iomap_swapfile_activate did not permit the use of
unwritten extents in the swap file.  Therefore, kick xfs out of the
always-supported list.

Fixes: 725feeff ("common/rc: swapon should not fail for given FS in _require_scratch_swapfile()")
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/common/rc b/common/rc
index 0fe1366..8e20749 100644
--- a/common/rc
+++ b/common/rc
@@ -2534,10 +2534,10 @@
 	# Minimum size for mkswap is 10 pages
 	_format_swapfile "$SCRATCH_MNT/swap" $(($(get_page_size) * 10))
 
-	# ext* and xfs have supported all variants of swap files since their
+	# ext* has supported all variants of swap files since their
 	# introduction, so swapon should not fail.
 	case "$FSTYP" in
-	ext2|ext3|ext4|xfs)
+	ext2|ext3|ext4)
 		if ! swapon "$SCRATCH_MNT/swap" >/dev/null 2>&1; then
 			_scratch_unmount
 			_fail "swapon failed for $FSTYP"