bug, nand, am33xx: nand->ecc.strength not set in board_nand_init()

commit dfe64e2c
Author: Sergey Lapin <slapin@ossfans.org>
Date:   Mon Jan 14 03:46:50 2013 +0000

    mtd: resync with Linux-3.7.1

Introduced runtime bug:

U-Boot 2013.04-00499-g46567df-dirty (Jun 04 2013 - 08:17:08)

I2C:   ready
DRAM:  512 MiB
WARNING: Caches not enabled
NAND:  BUG: failure at nand_base.c:3214/nand_scan_tail()!
BUG!
resetting ...

on boards using drivers/mtd/nand/omap_gpmc.c as in board_nand_init()
nand->ecc.strength is not set. Fix this!

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: Sergey Lapin <slapin@ossfans.org>
Cc: Scott Wood <scottwood@freescale.com>
Cc: Tom Rini <trini@ti.com>