mtd: rawnand: atmel: Fix dma_mapping_error() address

It seems like what was intended is to test if the dma_map of the
previous line failed but the wrong dma address was passed.

Fixes: f88fc122 ("mtd: nand: Cleanup/rework the atmel_nand driver")
Signed-off-by: Thomas Fourier <fourier.thomas@gmail.com>
Rule: add
Link: https://lore.kernel.org/stable/20250702064515.18145-2-fourier.thomas%40gmail.com


Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>