xfs: add missing include dependencies to xfs_dir2.h

xfs: add missing include dependencies to xfs_dir2.h

Source kernel commit: b597dd5373a1ccc08218665dc8417433b1c09550

xfs_dir2.h dereferences some data types in inline functions
and fails to include those type definitions, e.g.:
xfs_dir2_data_aoff_t, struct xfs_da_geometry.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-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>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>