ARM: dts: msm: change msm-audio-ion as child node of apr on sm8150

During bootup, ION probe may get called before adsp up notification
arrives. And it would fail to register ION SMMU which would cause
playback or record has no sound.
Move msm-audio-ion as child node of apr to make sure ION probe is called
after adsp up notification arrives.

Change-Id: If94ea8e2cab48f448a3f4bc43270f0f5ccd6acee
Signed-off-by: Meng Wang <mwang@codeaurora.org>