drm/i915/opregion: convert to struct intel_display

Going forward, struct intel_display shall replace struct
drm_i915_private as the main display device data pointer type. Convert
intel_opregion.[ch] to struct intel_display.

v2:
- Fix declarations for !CONFIG_ACPI (Imre, kernel test robot)
- Pass encoder/connector directly to intel_display() (Imre)

Reviewed-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/aef94503909bbbf95f0244dc382a4d4cd050b903.1723213547.git.jani.nikula@intel.com


Signed-off-by: Jani Nikula <jani.nikula@intel.com>