mtd: nand/fsmc: Read only 512 + 13 bytes for 8bit NAND devices

The ECC logic of FSMC works on 512 bytes data + 13 bytes ECC to generate error
indices of up to 8 incorrect bits. The FSMC driver reads 14 instead of 13 oob
bytes to accommodate for 16 bit device as well.

Unfortunately, the internal ecc state machine gets corrupted for 8 bit devices
reading 512 + 14 bytes of data resulting in error indices not getting reported.

Fix this by reading 14 bytes only for 16 bit devices

Signed-off-by: Vipin Kumar <vipin.kumar@st.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/nand/fsmc_nand.c

@@ -549,7 +549,9 @@ static int fsmc_read_page_hwecc(struct mtd_info *mtd, struct nand_chip *chip,
 			 * to read at least 13 bytes even in case of 16 bit NAND
 			 * devices
 			 */
-			len = roundup(len, 2);
+			if (chip->options & NAND_BUSWIDTH_16)
+				len = roundup(len, 2);
+
 			chip->cmdfunc(mtd, NAND_CMD_READOOB, off, page);
 			chip->read_buf(mtd, oob + j, len);
 			j += len;