sunxi: Add qt840a board

This board is indentical to the i12-tvbox board, but it has only 1 dram
ic soldered on, so it uses a 16 bit rather then a 32 bit bus for the dram.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
sunxi-mmc: sun6i has its fifo at a different address

This fixes the mmc code no longer working on sun6i after the changes to stop
using dma.

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