drm/bridge: sii902x: use display info is_hdmi

Use the pre-parsed information instead of parsing EDID again.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/9350875730b332ab2cac58fcbe7f4812fab567b8.1706038510.git.jani.nikula@intel.com