Fix FREEZE/THAW compat_ioctl regression

Commit 8e961870

 removed the FREEZE/THAW
handling in xfs_compat_ioctl but never added any compat handler back, so
now any freeze/thaw request from a 32-bit binary ond 64-bit userspace
will fail.

As these ioctls are 32/64-bit compatible two simple COMPATIBLE_IOCTL
entries in fs/compat_ioctl.c will do the job.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>