ASoC: lpass-platform: initialize dma channel number

ASoC: lpass-platform: initialize dma channel number

A bugfix accidentally removed the implicit initialization of the
dma channel number, causing undefined behavior when
v->alloc_dma_channel is NULL:

sound/soc/qcom/lpass-platform.c: In function ‘lpass_platform_pcmops_open’:
sound/soc/qcom/lpass-platform.c:83:29: error: ‘dma_ch’ may be used uninitialized in this function [-Werror=maybe-uninitialized]

This adds back an explicit initialization to zero, restoring the
previous behavior for that case.

Fixes: 022d00ee0b55 ("ASoC: lpass-platform: Fix broken pcm data usage")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Kenneth Westfield <kwestfie@codeaurora.org>
Signed-off-by: Mark Brown <broonie@kernel.org>