drm/xe: Rename MEM_SET instruction

PVC_MS_* doesn't reflect the real name of the instruction. Rename
it to follow the name used in the bspec.

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/20230929213640.3189912-3-lucas.demarchi@intel.com


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