NAND: Add hardware ECC support to the PPC4xx NAND driver ndfc.c

This patch adds hardware ECC support to the NDFC driver. It also
changes the register access from using the "simple" in32/out32
functions to the in_be32/out_be32 functions, which make sure
that the access is correctly synced. This is the only recommended
access to SoC registers in the current Linux kernel.

Signed-off-by: Stefan Roese <sr@denx.de>