xfs: don't call xfs_file_open from xfs_dir_open

Directories do not support direct I/O and thus no non-blocking direct
I/O either.  Open code the shutdown check and call to generic_file_open
instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240423124608.537794-4-hch@lst.de


Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>