ASoC: mt2701: remove unused variables

sound/soc/mediatek/mt2701/mt2701-afe-pcm.c:799:38: warning:
 mt2701_afe_o23_mix defined but not used [-Wunused-const-variable=]
sound/soc/mediatek/mt2701/mt2701-afe-pcm.c:803:38: warning:
 mt2701_afe_o24_mix defined but not used [-Wunused-const-variable=]
sound/soc/mediatek/mt2701/mt2701-afe-pcm.c:835:38: warning:
 mt2701_afe_multi_ch_out_i2s4 defined but not used [-Wunused-const-variable=]

They are never used, so can be removed.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20190813143811.31456-1-yuehaibing@huawei.com


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