mtd: spi-nor: use kernel sized types instead of c99 types

The kernel offers and prefers the kernel sized types instead of the c99
types when not in the uapi directory, use them.

Link: https://lore.kernel.org/r/20231101145853.524045-2-tudor.ambarus@linaro.org


Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>