Add NAND driver to support the Oxford Semiconductor OX820 NAND Controller.
This is a simple memory mapped NAND controller with single chip select and
software ECC.
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NNeil Armstrong <narmstrong@baylibre.com>
Signed-off-by: NBoris Brezillon <boris.brezillon@free-electrons.com>