drm/i915/skl: Enable the RPS interrupts programming

Enable the RPS interrupts programming(enable/disable/reset) for GEN9,
as missing changes to enable the RPS support on GEN9 have been added.

Signed-off-by: Akash Goel <akash.goel@intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>