synquacer: Introduce basic platform support

synquacer supports direct entry to BL31 without BL1 and BL2 as
SCP firmware does similar work. So this patch adds BL31 stub APIs.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
diff --git a/plat/socionext/synquacer/include/platform_def.h b/plat/socionext/synquacer/include/platform_def.h
new file mode 100644
index 0000000..532cb65
--- /dev/null
+++ b/plat/socionext/synquacer/include/platform_def.h
@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef __PLATFORM_DEF_H__
+#define __PLATFORM_DEF_H__
+
+#include <common_def.h>
+
+#define CACHE_WRITEBACK_SHIFT		6
+#define CACHE_WRITEBACK_GRANULE		(1 << CACHE_WRITEBACK_SHIFT)
+
+#define PLATFORM_STACK_SIZE		0x400
+
+#define BL31_BASE			0x04000000
+#define BL31_SIZE			0x00080000
+#define BL31_LIMIT			(BL31_BASE + BL31_SIZE)
+
+#endif /* __PLATFORM_DEF_H__ */