drm/i915/mtl: Define engine context layouts

The part of the media and blitter engine contexts that we care about for
setting up an initial state on MTL are nearly similar to DG2 (and PVC).
The difference being PRT_BB_STATE being replaced with NOP.

For render/compute engines, the part of the context images are nearly
the same, although the layout had a very slight change --- one POSH
register was removed and the placement of some LRI/noops adjusted
slightly to compensate.

v2:
 - Dg2, mtl xcs offsets slightly vary. Use a separate offsets array(Bala)
 - Add missing nop in xcs offsets(Bala)
v3:
 - Fix the spacing for nop in xcs offset(MattR)
v4:
 - Fix rcs register offset(MattR)
v4.1:
 - Fix commit message(Lucas)

Bspec: 46261, 46260, 45585
Cc: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Cc: Licas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220928155511.2379663-1-radhakrishna.sripada@intel.com