mtd: rawnand: atmel: Unmap streaming DMA mappings

Every dma_map_single() call should have its dma_unmap_single() counterpart,
because the DMA address space is a shared resource and one could render the
machine unusable by consuming all DMA addresses.

Link: https://lore.kernel.org/lkml/13c6c9a2-6db5-c3bf-349b-4c127ad3496a@axentia.se/


Cc: stable@vger.kernel.org
Fixes: f88fc122 ("mtd: nand: Cleanup/rework the atmel_nand driver")
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Acked-by: Alexander Dahl <ada@thorsis.com>
Reported-by: Peter Rosin <peda@axentia.se>
Tested-by: Alexander Dahl <ada@thorsis.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Tested-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220728074014.145406-1-tudor.ambarus@microchip.com