spi: spi-cadence: Delete unmatched comments

The function no longer returns a value, synchronize the comments.

Signed-off-by: Yangtao Li <frank.li@vivo.com>
Link: https://lore.kernel.org/r/20230712064832.67091-1-frank.li@vivo.com


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