ASoC: mediatek: mtk-btcvsd: Add checks for write and read of mtk_btcvsd_snd

As the mtk_btcvsd_snd_write and mtk_btcvsd_snd_read may return error,
it should be better to catch the exception.

Fixes: 4bd8597d ("ASoC: mediatek: add btcvsd driver")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Link: https://lore.kernel.org/r/20221116030750.40500-1-jiasheng@iscas.ac.cn


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