Fix system audio mode failure in boot up

This bug happens because <Set System Audio Mode> is arrived
before <Give System Audio Mode Status>'s send result callback
is called in service thread. We do set internal state
on callback resut.
This change sets state when we send command.
Along with this, add more debug log to help future debugging.

Bug: 17309726
Change-Id: I0e41f684372a4c8891a90f724944227fc689e053