ARM: sun6i: Add MMC0 controller to the Colombus board

The Colombus has a full size SD slot wired to the MMC0 controller. In order to
work, the MMC lines have to have the pull-ups enabled though.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>