drm/i915: Skip Bit12 fw domain reset for gen12+

Bit12 of the Forcewake request register should not be cleared post
gen12. Do not touch this bit while clearing during fw domain reset.

v2: Tweak the comment to drop older platforms(MattR)

Bspec: 52542

Signed-off-by: Sushma Venkatesh Reddy <sushma.venkatesh.reddy@intel.com>
Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220817224304.255767-1-radhakrishna.sripada@intel.com