drm/i915/bios: no need to pass i915 to parse_ddi_port()

i915 is available via devdata, grab it there instead of passing.

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/45c97c93bb9262c08aefa7b4bfe31f3f3481c998.1654870175.git.jani.nikula@intel.com