drm/i915: re-disable RC6p on Sandy Bridge

drm/i915: re-disable RC6p on Sandy Bridge

commit 67b0b4ed259e425b7eed09da75b42c80682ca003 upstream.

RC6p on Sandy Bridge got re-enabled over time, causing visual glitches
and GPU hangs.

Disabled originally in commit 2a8ec16698af ("drm/i915: do not enable
RC6p on Sandy Bridge").

Signed-off-by: Sasa Dragic <sasa.dragic@gmail.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221219172927.9603-2-sasa.dragic@gmail.com
Fixes: ae610790ebd5 ("drm/i915: Remove unsafe i915.enable_rc6")
Fixes: daade467b8c8 ("drm/i915/gt: Select the deepest available parking mode for rc6")
Cc: stable@vger.kernel.org
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
(cherry picked from commit 0c8a6e9ea232c221976a0670256bd861408d9917)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>