drm/i915/xehp: CCS should use RCS setup functions

The compute engine handles the same commands the render engine can
(except 3D pipeline), so it makes sense that CCS is more similar to RCS
than non-render engines.

The CCS context state (lrc) is also similar to the render one, so reuse
it. Note that the compute engine has its own CTX_R_PWR_CLK_STATE
register.

In order to avoid having multiple RCS && CCS checks, add the following
engine flag:
 - I915_ENGINE_HAS_RCS_REG_STATE - use the render (larger) reg state ctx.

BSpec: 46260
Original-author: Michel Thierry
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Aravind Iddamsetty <aravind.iddamsetty@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220301231549.1817978-6-matthew.d.roper@intel.com