SPM(BL32) and hafnium(BL33) expect their manifest base address in x0
register, which is updated during BL2 stage by parsing fw_config.
In case of RESET_TO_BL31 it has to be updated while populating
entry point information.

Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: I6f4a97f3405029bd6ba25f0935e2d1f74bb95517