xfs: devirtualize ->sf_get_parent_ino and ->sf_put_parent_ino

The parent inode handling is the same for all directory format variants,
just use direct calls instead of going through a pointless indirect
call.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>