drm/i915/dsi: convert vlv_dsi.[ch] to struct intel_display

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

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://lore.kernel.org/r/320449f3b58c6eca6fdbb16e4e819cd0e133887a.1742554320.git.jani.nikula@intel.com


Signed-off-by: Jani Nikula <jani.nikula@intel.com>