xfs: Use generic_file_open()

Remove the open-coded check of O_LARGEFILE.  This changes the errno
to be the same as other filesystems; it was changed generically in
2.6.24 but that fix skipped XFS.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>