spi: rzv2m-csi: Add missing include

Add missing include of bits.h file.

Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@renesas.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20230715010407.1751715-2-fabrizio.castro.jz@renesas.com


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