drm/i915: split out intel_pm_types.h

This is far from ideal, but it reduces the i915_drv.h dependency from
intel_display_types.h. Maybe in the future we'll need a better split.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/c6c60d9a8f6dcd1fa2f4b187000c5bb6843a1371.1638366969.git.jani.nikula@intel.com