ARM Platforms: Load HW_CONFIG in BL2

The patch adds the necessary changes to load HW_CONFIG in BL2 for
ARM Platforms :

1. The load address of HW_CONFIG is specified via the `hw_config_addr`
property in TB_FW_CONFIG is loaded by BL1. The `hw_config_max_size`
property defines the maximum size to be expected for the HW_CONFIG.
The `arm_dyn_cfg_helpers.c` and corresponding header implements
utility functions to parse these DT properties defined.
The `arm_dyn_cfg.c` implements wrappers to these helpers to enable
them to be invoked from ARM platform layer.

2. `HW_CONFIG` is added to the `bl2_mem_params_descs[]` array which is
the list of images to be loaded by BL2.

3. The `libfdt` sources are now included when BL2 is built

4. A new helper `populate_next_bl_params_config()` is introduced in
desc_image_load.c to populate the subsequent executable BL images
with the `hw_config` and the corresponding `fw_config` if available.
The `plat_get_next_bl_params()` API for ARM platforms is modified to
invoke this new helper.

5. The implementation of `bl2_early_platform_setup2()` is modified to
consider `arg0` as well in addition to `arg1` passed from BL1.

6. Bump up the BL2 size for Juno to accommodate the inclusion of libfdt.

Change-Id: I80f1554adec41753e0d179a5237364f04fe13a3f
Signed-off-by: Soby Mathew <soby.mathew@arm.com>
diff --git a/plat/arm/common/arm_io_storage.c b/plat/arm/common/arm_io_storage.c
index 6d8f209..5cabc54 100644
--- a/plat/arm/common/arm_io_storage.c
+++ b/plat/arm/common/arm_io_storage.c
@@ -57,6 +57,10 @@
 	.uuid = UUID_TB_FW_CONFIG,
 };
 
+static const io_uuid_spec_t hw_config_uuid_spec = {
+	.uuid = UUID_HW_CONFIG,
+};
+
 #if TRUSTED_BOARD_BOOT
 static const io_uuid_spec_t tb_fw_cert_uuid_spec = {
 	.uuid = UUID_TRUSTED_BOOT_FW_CERT,
@@ -156,6 +160,11 @@
 		(uintptr_t)&tb_fw_config_uuid_spec,
 		open_fip
 	},
+	[HW_CONFIG_ID] = {
+		&fip_dev_handle,
+		(uintptr_t)&hw_config_uuid_spec,
+		open_fip
+	},
 #if TRUSTED_BOARD_BOOT
 	[TRUSTED_BOOT_FW_CERT_ID] = {
 		&fip_dev_handle,