drm/i915: Update gen12 forcewake table

drm/i915: Update gen12 forcewake table

The bspec's forcewake page was very stale and out of date for recent
platforms.  The hardware team finally provided us with an updated gen12
table (which applies to TGL, RKL, and DG1) and there are a lot of
changes.

v2:
 - Add comments showing the subregions of ranges that we've combined for
   ease of code review.  (Jose)
 - Rebase on the s/FORCEWAKE_BLITTER/FORCEWAKE_GT/ patch

Bspec: 66696
Cc: Caz Yokoyama <caz.yokoyama@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201009194442.3668677-3-matthew.d.roper@intel.com
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>