mtd: nand: jz4780: driver for NAND devices on JZ4780 SoCs

Add a driver for NAND devices connected to the NEMC on JZ4780 SoCs, as
well as the hardware BCH controller. DMA is not currently implemented.

While older 47xx SoCs also have a BCH controller, they are incompatible
with the one in the 4780 due to differing register/bit positions, which
would make implementing a common driver for them quite messy.

Signed-off-by: Alex Smith <alex.smith@imgtec.com>
Cc: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: linux-mtd@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Harvey Hunt <harvey.hunt@imgtec.com>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
[Brian: fixed a few small mistakes]
Signed-off-by: Brian Norris <computersforpeace@gmail.com>