xfs_restore: remove DMAPI support

The last of the DMAPI stubs were removed from Linux 5.17, so drop this
functionality altogether.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Tested-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>