Update to reflect new priorities for A2DP profile.

1. PRIORITY_OFF is when it is unchecked.
2. PRIORITY_ON is when it is checked.
3. PRIORITY_AUTO_CONNECT is when we want to auto connect.

When the box is checked, we want to auto connect,
so set the priority to AUTO_CONNECT.
When the user disconnects, we set the priority back
to PRIORITY_ON.