spi: s3c64xx: explicitly include <linux/bits.h>

The driver uses GENMASK() but does not include <linux/bits.h>.

It is good practice to directly include all headers used, it avoids
implicit dependencies and spurious breakage if someone rearranges
headers and causes the implicit include to vanish.

Include the missing header.

Reviewed-by: Peter Griffin <peter.griffin@linaro.org>
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Link: https://lore.kernel.org/r/20240207120431.2766269-4-tudor.ambarus@linaro.org


Signed-off-by: Mark Brown <broonie@kernel.org>