mtd: onenand: Store bad block marker position in chip struct

The information about where the manufacturer puts the bad block
markers inside the bad block and in the OOB data is stored in
different places. Let's move this information to the chip struct,
as we did it for rawnand.

Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>