drm/xe: add MTL mocs
It was incorrectly using dg2_mocs for now.
Straight import from https://github.com/intel-innersource/drivers.gpu.i915.drm-intel/blob/dii-client/drivers/gpu/drm/i915/gt/intel_mocs.c
Signed-off-by: Philippe Lecluse philippe.lecluse@intel.com