[MTD] [NAND] nandsim: bugfix in initialization

NAND of > 32MiB in size use 4 bytes in address cycle, not 3.

Reported-by: bhsong <bhsong@augustatek.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>