AudioService: fix audio mode lock

Fix lock "sharing" for audio mode, with locking order as
1/ AudioDeviceBroker.mSetModeLock
2/ AudioDeviceBroker.mDeviceStateLock
3/ BtHelper class

The following code paths have been automatically generated
  as accessing BtHelper.requestScoState(int, int), which
  requires the lock to mSetModeLock. They have been checked
  for consistency of locks, and have been fixed and/or annotated:

ScoClient in BtHelper.decCount()  (com.android.server.audio)
    BtHelper.stopBluetoothScoForClient(IBinder, String)  (com.android.server.audio)
        AudioDeviceBroker.stopBluetoothScoForClient_Sync(IBinder, String)  (com.android.server.audio)
            AudioService.stopBluetoothSco(IBinder)  (com.android.server.audio)
ScoClient in BtHelper.incCount(int)  (com.android.server.audio)
    BtHelper.startBluetoothScoForClient(IBinder, int, String)  (com.android.server.audio)
        AudioDeviceBroker.startBluetoothScoForClient_Sync(IBinder, int, String)  (com.android.server.audio)
            AudioService.startBluetoothScoInt(IBinder, int, String)  (com.android.server.audio)
ScoClient in BtHelper.clearCount(boolean)  (com.android.server.audio)
    BtHelper.clearAllScoClients(int, boolean)  (com.android.server.audio)
        BtHelper.disconnectBluetoothSco(int)  (com.android.server.audio)
            BrokerHandler in AudioDeviceBroker.handleMessage(Message)  (com.android.server.audio)
        BtHelper.resetBluetoothSco()  (com.android.server.audio)
            BrokerHandler in AudioDeviceBroker.handleMessage(Message)  (com.android.server.audio)
            BtHelper.setBtScoActiveDevice(BluetoothDevice)  (com.android.server.audio)
                BtHelper.disconnectHeadset()  (com.android.server.audio)
                    BrokerHandler in AudioDeviceBroker.handleMessage(Message)  (com.android.server.audio)
                BtHelper.receiveBtEvent(Intent)  (com.android.server.audio)
                    AudioDeviceBroker.receiveBtEvent(Intent)  (com.android.server.audio)
                BtHelper.onHeadsetProfileConnected(BluetoothHeadset)  (com.android.server.audio)
                    BrokerHandler in AudioDeviceBroker.handleMessage(Message)  (com.android.server.audio)
            BtHelper.onSystemReady()  (com.android.server.audio)
                AudioDeviceBroker.onSystemReady()  (com.android.server.audio)
        BtHelper.receiveBtEvent(Intent)  (com.android.server.audio)
    BtHelper.scoClientDied(Object)  (com.android.server.audio)
        BrokerHandler in AudioDeviceBroker.handleMessage(Message)  (com.android.server.audio)

Bug: 123769055
Test: see bug
Change-Id: I5fbb5e8c56d69b8ccfc6b2f44b00169c6b75b632