Add mock check and clear to RPMB mock backend tests

Check expected mocks to happen and clear mock registry to fix memory
leak in rpmb_backend_mock tests.

Signed-off-by: Imre Kis <imre.kis@arm.com>
Change-Id: If5316aece9d885e27c1dd9c010556fb16ff13f8d
diff --git a/components/service/rpmb/backend/mock/test/test_rpmb_backend_mock.cpp b/components/service/rpmb/backend/mock/test/test_rpmb_backend_mock.cpp
index 594ba3c..023f941 100644
--- a/components/service/rpmb/backend/mock/test/test_rpmb_backend_mock.cpp
+++ b/components/service/rpmb/backend/mock/test/test_rpmb_backend_mock.cpp
@@ -1,10 +1,11 @@
 /*
- * Copyright (c) 2023, Arm Limited. All rights reserved.
+ * Copyright (c) 2023-2024, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
 #include <CppUTest/TestHarness.h>
+#include <CppUTestExt/MockSupport.h>
 #include "../rpmb_backend_mock.h"
 #include <string.h>
 
@@ -17,6 +18,8 @@
 	TEST_TEARDOWN()
 	{
 		rpmb_backend_mock_deinit(&mock_backend);
+		mock().checkExpectations();
+		mock().clear();
 	}
 
 	struct rpmb_backend *backend;