ARM: shmobile: defconfig: Enable ADV7612 CEC support

Enable support for Consumer Electronics Control on the Analog Devices
ADV7612 HDMI receiver, which is used on the Koelsch and Lager boards.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200624131931.3686-7-geert+renesas@glider.be