mtd: rawnand: add defines for ONFI version bits

Add defines for the ONFI version bits and use them in
nand_flash_detect_onfi().

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>