nand_bbt.c

This brings the core NAND code up to date with the Linux kernel.

Since there were several drivers in Linux as of the last update that are
not in u-boot, I'm not bringing over new drivers that have been added
since in the absence of an interested party.

I did not update OneNAND since it was recently synced by Kyungmin Park,
and I'm not sure exactly what the common ancestor is.

Signed-off-by: Scott Wood <scottwood@freescale.com>