bl2-el3: Add BL2_EL3 image

This patch enables BL2 to execute at the highest exception level
without any dependancy on TF BL1. This enables platforms which already
have a non-TF Boot ROM to directly load and execute BL2 and subsequent BL
stages without need for BL1.  This is not currently possible because
BL2 executes at S-EL1 and cannot jump straight to EL3.

Change-Id: Ief1efca4598560b1b8c8e61fbe26d1f44e929d69
Signed-off-by: Roberto Vargas <roberto.vargas@arm.com>
diff --git a/plat/common/plat_bl2_el3_common.c b/plat/common/plat_bl2_el3_common.c
new file mode 100644
index 0000000..358a02d
--- /dev/null
+++ b/plat/common/plat_bl2_el3_common.c
@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch_helpers.h>
+#include <assert.h>
+#include <bl_common.h>
+#include <debug.h>
+#include <errno.h>
+#include <platform_def.h>
+
+/*
+ * The following platform functions are weakly defined. They
+ * are default implementations that allow BL2 to compile in
+ * absence of real definitions. The Platforms may override
+ * with more complex definitions.
+ */
+#pragma weak bl2_el3_plat_prepare_exit
+
+void bl2_el3_plat_prepare_exit(void)
+{
+}