drm/i915/icl: Wa_2006665173

Disable blend embellishment in RCC.

Also, some other registers style fixed in passing.

v2: Rebased on top of the WA refactoring
v3: Added References (Mika)
v4:
  - Fixed in B0
  - Mentioned style fixes in commit message

References: HSDES#2006665173
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1527285939-20113-4-git-send-email-oscar.mateo@intel.com