Fix build warning

... and use toString for more meaningfull pixel format value.

Bug: 338251124
Test: adb shell cmd -w virtual_camera enable_test_camera
Change-Id: I3791739cf3e0da8678e75def741921d26d0101a6
diff --git a/services/camera/virtualcamera/VirtualCameraTestInstance.cc b/services/camera/virtualcamera/VirtualCameraTestInstance.cc
index 5e1d450..bae871d 100644
--- a/services/camera/virtualcamera/VirtualCameraTestInstance.cc
+++ b/services/camera/virtualcamera/VirtualCameraTestInstance.cc
@@ -122,8 +122,8 @@
 ScopedAStatus VirtualCameraTestInstance::onStreamConfigured(
     const int32_t streamId, const Surface& surface, const int32_t width,
     const int32_t height, const Format pixelFormat) {
-  ALOGV("%s: streamId %d, %dx%d pixFmt=%d", __func__, streamId, width, height,
-        pixelFormat);
+  ALOGV("%s: streamId %d, %dx%d pixFmt=%s", __func__, streamId, width, height,
+        toString(pixelFormat).c_str());
 
   std::lock_guard<std::mutex> lock(mLock);
   mRenderer = std::make_shared<TestPatternRenderer>(