drm/bridge: lt9611uxc: use drm_bridge_get_edid() instead of using ->get_edid directly

Make drm_bridge_get_edid() the one place to call the hook.

Cc: Andrzej Hajda <andrzej.hajda@intel.com>
Cc: Neil Armstrong <neil.armstrong@linaro.org>
Cc: Robert Foss <rfoss@kernel.org>
Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
Cc: Jonas Karlman <jonas@kwiboo.se>
Cc: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230914131450.2473061-2-jani.nikula@intel.com