drm/xe: Prepare to emit non-register state while recording default LRC

On some platforms we need to emit some non-register state while
recording an engine class' default LRC.  Add the infrastructure to
support this; actual per-platform tables will be added in future
patches.

v2:
 - Checkpatch whitespace fix
 - Add extra assertion to ensure num_dw != 0.  (Bala)

Reviewed-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Link: https://lore.kernel.org/r/20231025151732.3461842-6-matthew.d.roper@intel.com


Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>