This patch adds support for Firmware update in BL2U for ARM
platforms such that TZC initialization is performed on all
ARM platforms and (optionally) transfer of SCP_BL2U image on
ARM CSS platforms.

BL2U specific functions are added to handle early_platform and
plat_arch setup. The MMU is configured to map in the BL2U
code/data area and other required memory.

Change-Id: I57863295a608cc06e6cbf078b7ce34cbd9733e4f