Using the nand erase option "spread", maybe overwrite
blocks on, for example another mtd partition, if the
erasing range contains bad blocks.
So a limit option is added to nand_erase_opts()
Signed-off-by: Heiko Schocher <hs@denx.de> Cc: Scott Wood <scottwood@freescale.com> Cc: Pantelis Antoniou <panto@antoniou-consulting.com> Cc: Lukasz Majewski <l.majewski@samsung.com> Cc: Kyungmin Park <kyungmin.park@samsung.com> Cc: Marek Vasut <marex@denx.de> Cc: Tom Rini <trini@ti.com> Signed-off-by: Scott Wood <scottwood@freescale.com>