soc: add snd_event_init func for mark audio KPI

snd_event_dlkm is loaded as the first module.
Add init function and place mark in it to indicate the
start time of audio driver initialization.

Change-Id: Ie0c85b9166686d91f71ff773224eca59d85a36e5
Signed-off-by: Hongtao Peng <hongtaop@codeaurora.org>