mtd: nand_base: allow drivers to choose ECC block size

This patch allows core driver to choose ECC block size in
sw ecc case.

Signed-off-by: Vimal Singh <vimalsingh@ti.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/nand/nand_base.c

@@ -2728,7 +2728,8 @@ int nand_scan_tail(struct mtd_info *mtd)
 		chip->ecc.write_page_raw = nand_write_page_raw;
 		chip->ecc.read_oob = nand_read_oob_std;
 		chip->ecc.write_oob = nand_write_oob_std;
-		chip->ecc.size = 256;
+		if (!chip->ecc.size)
+			chip->ecc.size = 256;
 		chip->ecc.bytes = 3;
 		break;