drm/i915/irq: convert rest of intel_display_irq.[ch] to struct intel_display

Going forward, struct intel_display is the main display device data
pointer. Convert as much as possible of intel_display_irq.[ch] to struct
intel_display.

Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://lore.kernel.org/r/b6e281875278ad84772938f81129fde6065b2745.1742481923.git.jani.nikula@intel.com