[MTD] Add Amstrad Delta NAND support

The patch below adds support for the NAND device on the Amstrad Delta.
This is a 32MiB 8bit Toshiba device, with the data bus connected to the
OMAP MPUIO pins and ALE, CLE, NCE, NRE, NWE and NWP all connected to the
Delta's latch2 16bit latch.

Signed-Off-By: Jonathan McDowell <noodles@earth.li>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>