drm/xe: Adjust mocs field mask definitions

Instead of using xe_mocs_index_to_value(), simply define the bitmask
with the shift left applied. This will make it easier to adapt to new
platforms that simply use the index.

This also fixes PVC bug in emit_clear_link_copy() where the MOCS was
getting shifted both by PVC_MS_MOCS_INDEX_MASK definition and by the
xe_moc_index_to_value function.

Bspec: 44509
Cc: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Haridhar Kalvala <haridhar.kalvala@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20230929213640.3189912-2-lucas.demarchi@intel.com


Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>