ASoC: mediatek: common: Handle mediatek,accdet property

Handle the optional mediatek,accdet property. When present, retrieve the
sound component from its phandle, so the machine sound driver can use it
to register the audio jack and initialize the MT6359 ACCDET for jack
detection.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>