drm/i915: Move eDP scaling_mode prop setup to the proper place

We have an eDP specific intel_edp_add_properties() so move
the eDP scaling_mode property setup there from
intel_dp_add_properties().

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220912111814.17466-11-ville.syrjala@linux.intel.com


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