drm/i915/pps: convert intel_pps.[ch] 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_pps.[ch] to struct intel_display.

Some stragglers are left behind where needed.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/bea51b0d9e4546ba21d0d4eb01ca1097fda095ab.1725012870.git.jani.nikula@intel.com