sunxi: Enable composite video out on the CHIP

The CHIP has a composite video output in the mini-Jack connector, alongside
with the 2 audio channels. Enable this output in U-Boot.

Signed-off-by: Alex Kaplan <kaplan2539@gmail.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>