drm/i915/mtl: Fix bcs default context

drm/i915/mtl: Fix bcs default context

Commit 0d0e7d1eea9e ("drm/i915/mtl: Define engine context layouts")
added the engine context for Meteor Lake. In a second revision of the
patch it was believed the xcs offsets were wrong due to a tagging
issue in the spec. The first version was actually correct, as shown
by the intel_lrc_live_selftests/live_lrc_layout test:

	i915: Running gt_lrc
	i915: Running intel_lrc_live_selftests/live_lrc_layout
	bcs0: LRI command mismatch at dword 1, expected 1108101d found 11081019
	[drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] [CONNECTOR:236:DP-1] disconnected
	bcs0: HW register image:
	[0000] 00000000 1108101d 00022244 ffff0008 00022034 00000088 00022030 00000088
	...
	bcs0: SW register image:
	[0000] 00000000 11081019 00022244 00090009 00022034 00000000 00022030 00000000

The difference in the 2 additional dwords (0x1d vs 0x19) are the offsets
 0x120 / 0x124 that are indeed part of the context image.

Bspec: 45585

Fixes: 0d0e7d1eea9e ("drm/i915/mtl: Define engine context layouts")
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230111235531.3353815-2-radhakrishna.sripada@intel.com
(cherry picked from commit ca54a9a32da0f0ef7e5cbcd111b66f3c9d78b7d2)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>