drm/i915/display: convert high level power interfaces to struct intel_display

Going forward, struct intel_display is the main device data structure
for display. Convert the high level interfaces (init, cleanup, suspend,
resume, etc.) of intel_display_power.c over to it. The actual power
get/put etc. are left for follow-up.

Cc: Imre Deak <imre.deak@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/e1761b0fe5081bf6ca21cca3430befe254f61b32.1732808222.git.jani.nikula@intel.com