Fix direct/offload thread output devices into MSD

Without this change, direct/offload threads show
"Output devices:  (Empty device types)". Empty device
causes timestamp correction to always be disabled for
output threads requiring timestamp correction.

Test: check direct/offload output into MSD dumpsys output devices
      atest audiopolicy_tests
Bug: 159948389
Change-Id: I7006c9da2f0a228dd49ce0297c30035fef983090
diff --git a/services/audiopolicy/tests/AudioPolicyManagerTestClient.h b/services/audiopolicy/tests/AudioPolicyManagerTestClient.h
index e1721ea..bdddf06 100644
--- a/services/audiopolicy/tests/AudioPolicyManagerTestClient.h
+++ b/services/audiopolicy/tests/AudioPolicyManagerTestClient.h
@@ -75,6 +75,10 @@
     status_t createAudioPatch(const struct audio_patch *patch,
                               audio_patch_handle_t *handle,
                               int /*delayMs*/) override {
+        auto iter = mActivePatches.find(*handle);
+        if (iter != mActivePatches.end()) {
+            mActivePatches.erase(*handle);
+        }
         *handle = mNextPatchHandle++;
         mActivePatches.insert(std::make_pair(*handle, *patch));
         return NO_ERROR;