mtd: nand: Add OX820 NAND Support
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: Rob Herring <robh@kernel.org> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>