drm/i915/gt: skip WA verification for GEN7_MISCCPCTL on DG2

drm/i915/gt: skip WA verification for GEN7_MISCCPCTL on DG2

Some DG2 firmware locks this register for modification. Using wa_add
with read_mask 0 allows to skip checks of such registers.

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8945
Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230912073521.2106162-1-andrzej.hajda@intel.com