drm/i915/display: convert intel_display_driver.[ch] to struct intel_display

drm/i915/display: convert intel_display_driver.[ch] to struct intel_display

Going forward, struct intel_display will be the main display driver
structure. Convert the main display entry points to struct
intel_display.

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241204102150.2223455-1-jani.nikula@intel.com