drm/amdkfd: Update PM4 packet headers

To match current firmware. The map process packet has been extended
to support scratch. This is a non-backwards compatible change and
it's about two years old. So no point keeping the old version around
conditionally.

Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>