As nand_bb_write_buf calls mtd_write(bb->mtd, cur_ofs, now, ...) the
limit that now should be checked against is bb->mtd->size - cur_ofs.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>