mtd: rawnand: meson: set oob layout ops

Specify the oob layout operation to avoid no oob scheme defined for
some nand flash.

Fixes: 8fae856c ("mtd: rawnand: meson: add support for Amlogic NAND flash controller")
Signed-off-by: Liang Yang <liang.yang@amlogic.com>
Tested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>