os: introduce common platform driver for ARM

Ref #3299

repos/os/include/platform_device/capability.h

@@ -0,0 +1,19 @@
+/*
+ * \brief  Device capability type
+ * \author Norman Feske
+ * \date   2008-08-16
+ */
+
+/*
+ * Copyright (C) 2008-2017 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU Affero General Public License version 3.
+ */
+
+#pragma once
+
+#include <base/capability.h>
+#include <platform_device/platform_device.h>
+
+namespace Platform { typedef Genode::Capability<Device> Device_capability; }