drm/i915/psr: convert intel_psr.[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_psr.[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/4399b98b07019a8063adbec1043ff7eabb7c1080.1725012870.git.jani.nikula@intel.com