Add initial test driver conforming to the new spec

Also adjusted the different makefiles accordingly.
Note: driver lifetime is currently statically defined in the header, but
this will be replaced in the future based on autogeneration of lifetime
values by a script (TBD)

Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
diff --git a/tests/include/drivers/test_driver.h b/tests/include/drivers/test_driver.h
new file mode 100644
index 0000000..5494674
--- /dev/null
+++ b/tests/include/drivers/test_driver.h
@@ -0,0 +1,29 @@
+/*
+ * Umbrella include for all of the test driver functionality
+ */
+/*  Copyright (C) 2020, ARM Limited, All Rights Reserved
+ *  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://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.
+ *
+ *  This file is part of mbed TLS (https://tls.mbed.org)
+ */
+
+#ifndef MBEDTLS_PSA_CRYPTO_TEST_DRIVER_H
+#define MBEDTLS_PSA_CRYPTO_TEST_DRIVER_H
+
+#define MBEDTLS_PSA_CRYPTO_TEST_DRIVER_LIFETIME 0x7fffff
+
+#include "drivers/signature.h"
+
+#endif /* MBEDTLS_PSA_CRYPTO_TEST_DRIVER_H */