On platforms that support read L3 caching, set the default mocs index in
CCS RING_CMD_CTL to leverage the read caching in L3.

Currently PVC and Xe2 platforms have the support.

Bspec: 72161
Signed-off-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20230929051539.3157441-1-lucas.demarchi@intel.comSigned-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>