drm/i915: re-disable RC6p on Sandy Bridge

drm/i915: re-disable RC6p on Sandy Bridge

commit f6f6694c6bd684313cbed964f319fb5dcb1863df upstream.

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

Disabled originally in commit b29dcba037f2 ("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: d468671dd506 ("drm/i915: Remove unsafe i915.enable_rc6")
Fixes: 63e80bcccbe7 ("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 e9267da44c2b2c87a2eb91fb3dfe59d123fa2679)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>