mtd: spinand: macronix: use scratch buffer for DMA operation

The mx35lf1ge4ab_get_eccsr() function uses an SPI DMA operation to
read the eccsr, hence the buffer should not be on stack. Since commit
38058322 ("spi: spi-mem: Add extra sanity checks on the op param")
the kernel emmits a warning and blocks such operations.

Use the scratch buffer to get eccsr instead of trying to directly read
into a stack-allocated variable.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Reviewed-by: Dhruva Gole <d-gole@ti.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/Y8i85zM0u4XdM46z@makrotopia.org

drivers/mtd/nand/spi/macronix.c

@@ -83,9 +83,10 @@ static int mx35lf1ge4ab_ecc_get_status(struct spinand_device *spinand,
 		 * in order to avoid forcing the wear-leveling layer to move
 		 * data around if it's not necessary.
 		 */
-		if (mx35lf1ge4ab_get_eccsr(spinand, &eccsr))
+		if (mx35lf1ge4ab_get_eccsr(spinand, spinand->scratchbuf))
 			return nanddev_get_ecc_conf(nand)->strength;
 
+		eccsr = *spinand->scratchbuf;
 		if (WARN_ON(eccsr > nanddev_get_ecc_conf(nand)->strength ||
 			    !eccsr))
 			return nanddev_get_ecc_conf(nand)->strength;