mtd: spinand: macronix: Fix ECC Status Read

The datasheet specifies the upper four bits are reserved.
Testing on real hardware shows that these bits can indeed be nonzero.

Signed-off-by: Emil Lenngren <emil.lenngren@gmail.com>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

drivers/mtd/nand/spi/macronix.c

@@ -10,6 +10,7 @@
 #include <linux/mtd/spinand.h>
 
 #define SPINAND_MFR_MACRONIX		0xC2
+#define MACRONIX_ECCSR_MASK		0x0F
 
 static SPINAND_OP_VARIANTS(read_cache_variants,
 		SPINAND_PAGE_READ_FROM_CACHE_X4_OP(0, 1, NULL, 0),
@@ -55,7 +56,12 @@ static int mx35lf1ge4ab_get_eccsr(struct spinand_device *spinand, u8 *eccsr)
 					  SPI_MEM_OP_DUMMY(1, 1),
 					  SPI_MEM_OP_DATA_IN(1, eccsr, 1));
 
-	return spi_mem_exec_op(spinand->spimem, &op);
+	int ret = spi_mem_exec_op(spinand->spimem, &op);
+	if (ret)
+		return ret;
+
+	*eccsr &= MACRONIX_ECCSR_MASK;
+	return 0;
 }
 
 static int mx35lf1ge4ab_ecc_get_status(struct spinand_device *spinand,