xfs: define XFS_IOC_FREEZE even if FIFREEZE is defined

And the same for XFS_IOC_THAW.  Just because we now have a common
version of the ioctl we still need to provide the old name for it
for anyone using those.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>