arm64: defconfig: Enable Lontium LT9611 driver

Lontium LT9611 HDMI bridge can be found in Dragon Board RB3 for
converting DSI to HDMI. Enable this driver to get display working on RB3

Signed-off-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20200727080118.1934079-1-vkoul@kernel.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>