filesystem freeze: remove XFS specific ioctl interfaces for freeze feature

It removes XFS specific ioctl interfaces and request codes
for freeze feature.

This patch has been supplied by David Chinner.

Signed-off-by: Dave Chinner <dgc@sgi.com>
Signed-off-by: Takashi Sato <t-sato@yk.jp.nec.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: <xfs-masters@oss.sgi.com>
Cc: <linux-ext4@vger.kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Kleikamp <shaggy@austin.ibm.com>
Cc: Alasdair G Kergon <agk@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>