[XFS] Remove KERNEL_VERSION macros from xfs_dmapi.h

SGI-PV: 957005
SGI-Modid: xfs-linux-melb:xfs-kern:27398a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Michal Piotrowski <michal.k.k.piotrowski@gmail.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>