drm/i915/pps: drop dependency on intel_display_conversion.h

drm/i915/pps: drop dependency on intel_display_conversion.h

All the PPS register users have been converted to struct
intel_display. The backward compat conversion to struct drm_i915_private
is no longer needed. Drop it, along with the include, and convert the
dev_priv macro parameter names to display while at it.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://lore.kernel.org/r/4c23fd8dfcadefeeb52189045421084bcfd50d57.1747128495.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>