drm/i915: Re-use gen11 forcewake read functions on gen12

drm/i915: Re-use gen11 forcewake read functions on gen12

The forcewake read logic is identical between gen11 and gen12, only the
forcewake table data (which is tracked separately) differs; there's no
need to generate a separate set of gen12 read functions when the gen11
functions will work just as well.

We'll keep the separate write functions for now since the generated code
directly references different shadow tables between the two platforms.

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Caz Yokoyama <caz.yokoyama@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210729054118.2458523-3-matthew.d.roper@intel.com