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

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

Going forward, struct intel_display is the main display device data
pointer. Convert the external interfaces 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/83b552154761d2790d8c774707e8d7612037bdf5.1742481923.git.jani.nikula@intel.com