audio policy: acquire mutex in getDeviceConnecitonState

Add missing mutex locking in
AudioPolicyService::getDeviceConnectionState()

Bug: 215261795
Test: atest audiopolicy_tests
Change-Id: I9b13376e9d43e83bff3e21d2bb0455e1b78dc507
diff --git a/services/audiopolicy/service/AudioPolicyInterfaceImpl.cpp b/services/audiopolicy/service/AudioPolicyInterfaceImpl.cpp
index aba8884..87a350f 100644
--- a/services/audiopolicy/service/AudioPolicyInterfaceImpl.cpp
+++ b/services/audiopolicy/service/AudioPolicyInterfaceImpl.cpp
@@ -166,6 +166,7 @@
                         AUDIO_POLICY_DEVICE_STATE_UNAVAILABLE));
         return Status::ok();
     }
+    Mutex::Autolock _l(mLock);
     AutoCallerClear acc;
     *_aidl_return = VALUE_OR_RETURN_BINDER_STATUS(
             legacy2aidl_audio_policy_dev_state_t_AudioPolicyDeviceState(