mtd: rawnand: cadence: change bad block marker size

Increase bad block marker size from one byte to two bytes.
Bad block marker is handled by skip bytes feature of HPNFC.
Controller expects this value to be an even number.

Fixes: ec4ba01e ("mtd: rawnand: Add new Cadence NAND driver to MTD subsystem")
Cc: stable@vger.kernel.org
Signed-off-by: Piotr Sroka <piotrs@cadence.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/1581328530-29966-3-git-send-email-piotrs@cadence.com