sunxi: video: Add support for LCD panels which need to be configured via i2c

This commits adds support for configuring a a bitbang i2c controller, which
is used on some boards to configure the LCD panel (via i2c).

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>