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>

plat/socionext/synquacer/include/platform_def.h

+/*
+ * 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__ */

plat/socionext/synquacer/sq_bl31_setup.c

+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch.h>
+#include <arch_helpers.h>
+#include <platform_def.h>
+#include <assert.h>
+#include <bl_common.h>
+#include <debug.h>
+
+void bl31_early_platform_setup(bl31_params_t *from_bl2,
+				void *plat_params_from_bl2)
+{
+	/* There are no parameters from BL2 if BL31 is a reset vector */
+	assert(from_bl2 == NULL);
+	assert(plat_params_from_bl2 == NULL);
+}
+
+void bl31_platform_setup(void)
+{
+}
+
+void bl31_plat_runtime_setup(void)
+{
+}
+
+void bl31_plat_arch_setup(void)
+{
+}