mtd: nand: Add NAND controller driver for OcteonTX

Adds support for NAND controllers found on OcteonTX or
OcteonTX2 SoC platforms. Also includes driver to support
Hardware ECC using BCH HW engine found on these platforms.

Signed-off-by: Aaron Williams <awilliams@marvell.com>
Signed-off-by: Suneel Garapati <sgarapati@marvell.com>
Signed-off-by: Stefan Roese <sr@denx.de>