audio: Verify that hal implements get_audio_port before calling

Change-Id: I3652382433d365407bf006d71f36743aa89a76ee
diff --git a/audio/core/all-versions/default/Device.cpp b/audio/core/all-versions/default/Device.cpp
index b954fcd..6e55e7b 100644
--- a/audio/core/all-versions/default/Device.cpp
+++ b/audio/core/all-versions/default/Device.cpp
@@ -401,6 +401,10 @@
 Return<void> Device::getAudioPortImpl(const AudioPort& port, getAudioPort_cb _hidl_cb,
                                       int (*halGetter)(audio_hw_device_t*, HalPort*),
                                       const char* halGetterName) {
+    if (halGetter == nullptr) {
+        _hidl_cb(Result::NOT_SUPPORTED, port);
+        return Void();
+    }
     HalPort halPort;
     if (status_t status = HidlUtils::audioPortToHal(port, &halPort); status != NO_ERROR) {
         _hidl_cb(analyzeStatus("audioPortToHal", status), port);