ASoC: ti: omap-mcbsp: use DEVICE_ATTR_RW macro

Use DEVICE_ATTR_RW() helper instead of plain DEVICE_ATTR(),
which makes the code a bit shorter and easier to read.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Jarkko Nikula <jarkko.nikula@bitmer.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@gmail.com>
Link: https://lore.kernel.org/r/20210528063033.19904-1-yuehaibing@huawei.com


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