ASoC: mediatek: dt-bindings: modify machine

Merge series from Chunxu Li <chunxu.li@mediatek.com>:

Add SOF related field.
1. Add a property "mediatek,adsp", Only when adsp phandle could be retrieved,
 from DTS, the SOF related part of machine driver is executed.
2. Add a property "mediatek,dai-link" to support dai-links could be specified
 from DTS