[MTD] OneNAND Simulator support

This simulate various OneNAND flash chips for the MTD onenand layer.
It's simple implementation, only basic operations.
It don't support the recent changes in NANDSIM such as lazy block allocation,
bitflip, and so on.

Note: This passed nand-tests.

Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>