Audio VTS: Always check for Result::isOk()

A test was not checking for the Result::isOk() resulting
in an assert being triggered in HIDL code if the HAL crashed.

Test: (sleep 0.3; adb shell pkill audio) &
      adb shell /data/nativetest64/VtsHalAudioV4_0TargetTest/VtsHalAudioV4_0TargetTest
      # Test finishes in failure but does not crash
Signed-off-by: Kevin Rocard <krocard@google.com>

Change-Id: I97a6213fe82a5e9a6eb333dc1dc2476102610b58
diff --git a/audio/core/4.0/vts/functional/AudioPrimaryHidlHalTest.cpp b/audio/core/4.0/vts/functional/AudioPrimaryHidlHalTest.cpp
index 0f8996f..59ced27 100644
--- a/audio/core/4.0/vts/functional/AudioPrimaryHidlHalTest.cpp
+++ b/audio/core/4.0/vts/functional/AudioPrimaryHidlHalTest.cpp
@@ -1402,6 +1402,7 @@
         "Make sure setBtHfpVolume is either not supported or "
         "only succeed if volume is in [0,1]");
     auto ret = device->setBtHfpVolume(0.0);
+    ASSERT_TRUE(ret.isOk());
     if (ret == Result::NOT_SUPPORTED) {
         doc::partialTest("setBtHfpVolume is not supported");
         return;