mtd: spinand: Improve spinand_info macros style

Let's assume all these macros should not have a trailing comma, this way
the caller can use a more formal and usual C writing style, as reflected
in the Macronix driver.

Acked-by: Pratyush Yadav <pratyush@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>