ASoC: msm: add machine drv as apr child node

Automotive machine driver is a child node of apr
so it will be re-probed upon ADSP UP event received
in APR driver during boot up.
Remove the dummy machine driver solution.

Change-Id: I9ac3e26366a5b01869183e8b83e47049ec770c7c
Signed-off-by: Derek Chen <chenche@codeaurora.org>