mtd: spinand: Propagate ECC information to the MTD structure

This is done by default in the raw NAND core (nand_base.c) but was
missing in the SPI-NAND core. Without these two lines the ecc_strength
and ecc_step_size values are not exported to the user through sysfs.

Fixes: 7529df46

 ("mtd: nand: Add core infrastructure to support SPI NANDs")
Cc: stable@vger.kernel.org
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Richard Weinberger <richard@nod.at>