mtd: spinand: winbond: Fix ecc_get_status

Reading ECC status is failing.

w25n02kv_ecc_get_status() is using on-stack buffer for
SPINAND_GET_FEATURE_OP() output. It is not suitable for
DMA needs of spi-mem.

Fix this by using the spi-mem operations dedicated buffer
spinand->scratchbuf.

See
spinand->scratchbuf:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/mtd/spinand.h?h=v6.3#n418
spi_mem_check_op():
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/spi/spi-mem.c?h=v6.3#n199

Fixes: 6154c7a ("mtd: spinand: winbond: add Winbond W25N02KV flash support")
Cc: stable@vger.kernel.org
Signed-off-by: Olivier Maignial <olivier.maignial@hotmail.fr>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/DB4P250MB1032EDB9E36B764A33769039FE23A@DB4P250MB1032.EURP250.PROD.OUTLOOK.COM

drivers/mtd/nand/spi/winbond.c

@@ -108,7 +108,7 @@ static int w25n02kv_ecc_get_status(struct spinand_device *spinand,
 {
 	struct nand_device *nand = spinand_to_nand(spinand);
 	u8 mbf = 0;
-	struct spi_mem_op op = SPINAND_GET_FEATURE_OP(0x30, &mbf);
+	struct spi_mem_op op = SPINAND_GET_FEATURE_OP(0x30, spinand->scratchbuf);
 
 	switch (status & STATUS_ECC_MASK) {
 	case STATUS_ECC_NO_BITFLIPS:
@@ -126,7 +126,7 @@ static int w25n02kv_ecc_get_status(struct spinand_device *spinand,
 		if (spi_mem_exec_op(spinand->spimem, &op))
 			return nanddev_get_ecc_conf(nand)->strength;
 
-		mbf >>= 4;
+		mbf = *(spinand->scratchbuf) >> 4;
 
 		if (WARN_ON(mbf > nanddev_get_ecc_conf(nand)->strength || !mbf))
 			return nanddev_get_ecc_conf(nand)->strength;