plat/arm: Rentroduce tb_fw_config device tree

Moved BL2 configuration nodes from fw_config to newly
created tb_fw_config device tree.

fw_config device tree's main usage is to hold properties shared
across all BLx images.
An example is the "dtb-registry" node, which contains the
information about the other device tree configurations
(load-address, size).

Also, Updated load-address of tb_fw_config which is now located
after fw_config in SRAM.

Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
Change-Id: Ic398c86a4d822dacd55b5e25fd41d4fe3888d79a
diff --git a/plat/arm/css/sgm/fdts/sgm_tb_fw_config.dts b/plat/arm/css/sgm/fdts/sgm_tb_fw_config.dts
index d481018..e416540 100644
--- a/plat/arm/css/sgm/fdts/sgm_tb_fw_config.dts
+++ b/plat/arm/css/sgm/fdts/sgm_tb_fw_config.dts
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */