xfs: remove the XFS_IOC_FSSETDM definitions

Remove the definitions for these ioctls, since the functionality (and,
weirdly, the 32-bit compat ioctl definitions) were removed from the
kernel in November 2019.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>