drm/i915/vblank: 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_vblank.[ch] to struct intel_display.

Some stragglers are left behind where needed.
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/40430651a45ddd9e350a1fd7938fe4054492f6ea.1724342644.git.jani.nikula@intel.comSigned-off-by: Jani Nikula <jani.nikula@intel.com>