Revert "drm/i915: Disable DC states for all commits"

This reverts commit 0fc6fea4 which is
commit a2b6e99d

 upstream.

It is reported to cause regression issues, so it should be reverted from
the 6.1.y tree for now.

Reported-by: Thorsten Leemhuis <regressions@leemhuis.info>
Link: https://lore.kernel.org/r/f0870e8f-0c66-57fd-f95d-18d014a11939@leemhuis.info
Link: https://gitlab.freedesktop.org/drm/intel/-/issues/8419
Cc: Manasi Navare <navaremanasi@google.com>
Cc: Drew Davenport <ddavenport@chromium.org>
Cc: Jouni Högander <jouni.hogander@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>