Fix the following coccicheck warning:

sound/soc/ti/omap-mcbsp.c:1188:5-11: WARNING: Comparison to bool
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Acked-by: Jarkko Nikula <jarkko.nikula@bitmer.com>
Link: https://lore.kernel.org/r/20200426094238.23914-1-yanaijie@huawei.comSigned-off-by: Mark Brown <broonie@kernel.org>