Camera NDK: don't explicit delete ACameraMetadata

To fix the warning in RefBase destructor.

Test: NDK CTS tests, and ARCore measure app.
Bug: 112775599
Change-Id: Ia448ac6d7e6c17699c16d287f65fc2826c9d7578
diff --git a/camera/ndk/impl/ACameraManager.h b/camera/ndk/impl/ACameraManager.h
index cc42f77..ce65769 100644
--- a/camera/ndk/impl/ACameraManager.h
+++ b/camera/ndk/impl/ACameraManager.h
@@ -186,7 +186,7 @@
     static void     deleteCameraIdList(ACameraIdList* cameraIdList);
 
     camera_status_t getCameraCharacteristics(
-            const char *cameraId, ACameraMetadata **characteristics);
+            const char* cameraId, android::sp<ACameraMetadata>* characteristics);
     camera_status_t openCamera(const char* cameraId,
                                ACameraDevice_StateCallbacks* callback,
                                /*out*/ACameraDevice** device);