plat/arm/juno: Add support to use hw_config in BL31

To make it possible to use the hw_config device tree for dynamic
configuration in BL31 on the Arm Juno platform. A placeholder hw_config
has been added that is included in the FIP and a Juno specific BL31
setup has been added to populate fconf with the hw_config.

Juno's BL2 setup has been updated to align it with the new behavior
implemented in the Arm FVP platform, where fw_config is passed in arg1
to BL31 instead of soc_fw_config. The BL31 setup is expected to use the
fw_config passed in arg1 to find the hw_config.

Signed-off-by: Mikael Olsson <mikael.olsson@arm.com>
Change-Id: Ib3570faa6714f92ab8451e8f1e59779dcf19c0b6
diff --git a/plat/arm/board/juno/juno_common.c b/plat/arm/board/juno/juno_common.c
index da4918c..cb183d5 100644
--- a/plat/arm/board/juno/juno_common.c
+++ b/plat/arm/board/juno/juno_common.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2020, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2021, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -75,6 +75,7 @@
 	ARM_V2M_MAP_MEM_PROTECT,
 #endif
 	SOC_CSS_MAP_DEVICE,
+	ARM_DTB_DRAM_NS,
 	{0}
 };
 #endif