Add protocol definitions for smm_variable

Adds protocol definition for the SMM Variable service. Protocol
files are based on EDK2 originals from:
https://github.com/tianocore/edk2/commits/master
b4da6c29f1d36031e04212f53277ce0dcba309f1
Structures and defines are required to be align for compatibility
between EDK2 and TS components.

Signed-off-by: Julian Hall <julian.hall@arm.com>
Change-Id: I3a478cdc5d3a849810abf6c699027f65594b4a83
diff --git a/protocols/service/smm_variable/smm_variable_proto.h b/protocols/service/smm_variable/smm_variable_proto.h
new file mode 100644
index 0000000..9e15bc1
--- /dev/null
+++ b/protocols/service/smm_variable/smm_variable_proto.h
@@ -0,0 +1,13 @@
+/*
+ * Copyright (c) 2021, Arm Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef TS_SMM_VARIABLE_PROTO_H
+#define TS_SMM_VARIABLE_PROTO_H
+
+#include <protocols/service/smm_variable/opcodes.h>
+#include <protocols/service/smm_variable/parameters.h>
+
+#endif /* TS_SMM_VARIABLE_PROTO_H */