[XFS] lose xfs_hex_dump in favor of print_hex_dump

No need for xfs to have its own hex dumping routine now that the kernel
has one.

SGI-PV: 971186
SGI-Modid: xfs-linux-melb:xfs-kern:29847a

Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>