Deprecate the Greentea metrics API

Add the deprecated macro to where the Greentea metrics API is declared.

Fixes #14790

features/frameworks/greentea-client/greentea-client/greentea_metrics.h

@@ -1,3 +1,22 @@
+/*
+ * mbed Microcontroller Library
+ * Copyright (c) 2006-2019 ARM Limited
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http:https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "platform/mbed_toolchain.h"
 
 /** \addtogroup frameworks */
 /** @{*/
@@ -7,11 +26,13 @@
 /**
  * Setup platform specific metrics
  */
+MBED_DEPRECATED_SINCE("mbed-os-6.13", "Greentea metrics API are deprecated")
 void greentea_metrics_setup(void);
 
 /**
  * Report and cleanup platform specifc metrics
  */
+MBED_DEPRECATED_SINCE("mbed-os-6.13", "Greentea metrics API are deprecated")
 void greentea_metrics_report(void);
 
 #endif