sunxi: nand: Add basic sunxi NAND driver for SPL with DMA support

This driver adds NAND support to SPL.
It was tested on Allwinner A20.

Signed-off-by: Peter Gielda <pgielda@antmicro.com>
Signed-off-by: Tomasz Gorochowik <tgorochowik@antmicro.com>
Signed-off-by: Mateusz Holenko <mholenko@antmicro.com>
Signed-off-by: Piotr Zierhoffer <pzierhoffer@antmicro.com>
Signed-off-by: Karol Gugala <kgugala@antmicro.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>