spi: Remove the @multi_cs_cap to prevent kernel-doc warnings

./include/linux/spi/spi.h:778: warning: Excess struct member 'multi_cs_cap' description in 'spi_controller'

Signed-off-by: R SUNDAR <prosunofficial@gmail.com>
Link: https://lore.kernel.org/r/20240204154506.3561-1-prosunofficial@gmail.com


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