FVP: Add dummy configs for BL31, BL32 and BL33

This patch adds soc_fw_config, tos_fw_config and nt_fw_config to the FVP.
The config files are placeholders and do not have any useful bindings
defined. The tos_fw_config is packaged in FIP and loaded by BL2 only
if SPD=tspd. The load address of these configs are specified in tb_fw_config
via new bindings defined for these configs. Currently, in FVP, the
soc_fw_config and tos_fw_config is loaded in the page between BL2_BASE
and ARM_SHARED_RAM. This memory was typically used for BL32 when
ARM_TSP_RAM_LOCATION=tsram but since we cannot fit BL32 in that
space anymore, it should be safe to use this memory for these configs.
There is also a runtime check in arm_bl2_dyn_cfg_init() which ensures
that this overlap doesn't happen.

The previous arm_dyn_get_hwconfig_info() is modified to accept configs
other than hw_config and hence renamed to arm_dyn_get_config_load_info().
The patch also corrects the definition of ARM_TB_FW_CONFIG_LIMIT to be
BL2_BASE.

Change-Id: I03a137d9fa1f92c862c254be808b8330cfd17a5a
Signed-off-by: Soby Mathew <soby.mathew@arm.com>