refactor(arm): simplify early platform setup function in BL31

Refactor `arm_bl31_early_platform_setup` to accept generic u_register_t
values, enabling support for firmware handoff boot arguments in
common code. This simplifies the interface for early platform setup.

Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Change-Id: Iff20300d2372e1a9825827ddccbd1b3bc6751e40
6 files changed