mtd: rawnand: atmel: Use nand_{write,read}_data_op()

mtd: rawnand: atmel: Use nand_{write,read}_data_op()

Use the nand_{write,read}_data_op() helpers instead of calling the
atmel_nand_{read,write}_buf() functions directly. This will ease the
transition to exec_op().

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200720131356.1579073-4-tudor.ambarus@microchip.com