Fix APM build with VV logging enabled

Test: manual build
Bug: 328830091
Change-Id: I5c4135d62fdaf8093571b5c035bd4f2d307732f8
diff --git a/services/audiopolicy/managerdefault/AudioPolicyManager.cpp b/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
index 449f1bd..dae8115 100644
--- a/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
+++ b/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
@@ -3907,7 +3907,7 @@
         _aidl_return.back().mToken = policyMix->mToken;
     }
 
-    ALOGVV("%s() returning %zu registered mixes", __func__, _aidl_return->size());
+    ALOGVV("%s() returning %zu registered mixes", __func__, _aidl_return.size());
     return OK;
 }