mtd: spinand: Remove write_enable_op() in markbad()

We don't have to call spinand_write_enable_op() in spinand_markbad() as
it is called in spinand_write_page().

Fixes: b645ad39 ("mtd: spinand: Do not erase the block before writing a bad block marker")
Signed-off-by: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>