mtd: nand: Request strength instead of bytes for soft BCH

Previously, we requested that drivers pass ecc.size and ecc.bytes when
using NAND_ECC_SOFT_BCH. However, a driver is likely to only know the ECC
strength required for its NAND, so each driver would need to perform a
strength-to-bytes calculation.

Avoid duplicating this calculation in each driver by asking drivers to
pass ecc.size and ecc.strength so that the strength-to-bytes calculation
need only be implemented once.

This reverts/generalizes this commit:
    mtd: nand: Base BCH ECC bytes on required strength

Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

drivers/mtd/nand/nandsim.c

@@ -2337,6 +2337,7 @@ static int __init ns_init_module(void)
 		}
 		chip->ecc.mode = NAND_ECC_SOFT_BCH;
 		chip->ecc.size = 512;
+		chip->ecc.strength = bch;
 		chip->ecc.bytes = eccbytes;
 		NS_INFO("using %u-bit/%u bytes BCH ECC\n", bch, chip->ecc.size);
 	}