Make sure the Hearing Aid source is ready before resuming or suspending calls

Those calls to resume / suspend streaming are from the audio's IPC
threads like HwBinder or UIPC, and calls to start / end session are from
the stack main thread. There is timing that those threads may run in
parallel, and trys to change the streaming state when the Hearing Aid
source is not ready. This change checks the source state before resuming
or suspending streaming, and breaks the deadlock between IPC threads and
the stack main thread.

Bug: 132860565
Test: 1. Connected to a Hearing Aids and disable the Bluetooth
      2. Switch the active device manually

Change-Id: I6ae11faab3d530c65f55ffa9b8a9f3cae2bde5f4