ASoC: mediatek: mt8195: add missing initialization

In etdm dai driver, dai_etdm_parse_of() function is used to parse dts
properties to get parameters. There are two for-loops which are
sepearately for all etdm and etdm input only cases. In etdm in only
loop, dai_id is not initialized, so it keeps the value intiliazed in
another loop.

In the patch, add the missing initialization to fix the unexpected
parsing problem.

Fixes: 1de9a54a

 ("ASoC: mediatek: mt8195: support etdm in platform driver")
Signed-off-by: Trevor Wu <trevor.wu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230301110200.26177-3-trevor.wu@mediatek.com
Signed-off-by: Mark Brown <broonie@kernel.org>