sunxi-hdmi-cec: Do not define own highres counter functionality

This is unnecessary code duplication, and more over, the implementation is
wrong as it sets the latch bit, but does not wait for it to clear again
before reading the counter. Which causes hdmi_delay_us to hang on mach-sun7i.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
video-sunxi: Add A20 support

Tested on the cubieboard2, with several different dvi/hdmi monitors. Note
lcd / vga / composite out is not tested.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>