drm/xe: add GSCCS ring ops

drm/xe: add GSCCS ring ops

Like the BCS, the GSCCS doesn't have any special HW that needs handling
when emitting commands, so we can re-use the same emit_job code. To make
it clear that this is now a shared low-level function, it has been
renamed to use the "simple" postfix, instead of "copy", to indicate that
it applies to all engines that don't need any additional engine-specific
handling.

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20230817201831.1583172-5-daniele.ceraolospurio@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>