arm64: defconfig: enable Lontium LT9611UXC bridge driver

Enable lt9611uxc driver for Lontium DSI to HDMI bridge found on Qualcomm
RB5 Robotics platform. Enable this driver to get display working on this
platform.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20201228151827.4019213-1-dmitry.baryshkov@linaro.org


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>