btrfs: replace open coded DEBUG_WARN in extent_writepage()

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -1868,7 +1868,7 @@ static int extent_writepage(struct folio *folio, struct btrfs_bio_ctrl *bio_ctrl
 	 * case.
 	 */
 	if (unlikely(!folio_test_private(folio))) {
-		WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));
+		DEBUG_WARN();
 		btrfs_err_rl(fs_info,
 	"root %lld ino %llu folio %llu is marked dirty without notifying the fs",
 			     btrfs_root_id(inode->root),