[MTD] [NAND] ndfc driver

The current ndfc driver only compiles under arch/ppc. This arch was
removed from the kernel. I notice the event entry for the ndfc in
Kconfig has been removed in 2.6.28.

This patch converts the ndfc to a proper OF (OpenFirmware) driver. I
can give a working example of the DTS if needed.

The patch has been in production use on the PIKA Warp Appliance and is
in use by others. The Warp basically boots from NAND, so the ndfc driver
is very important to us.

Signed-off-by: Sean MacLennan <smaclennan@pikatech.com>
Acked-By: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>