drm/i915: kill uncore_sanitize

uncore_sanitize performs no action on the uncore structure and just
calls intel_sanitize_gt_powersave, so we can just call the latter
directly.

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190620010021.20637-3-daniele.ceraolospurio@intel.com