firmware: Introduce relocation lottery

Instead of forcing HART0 to do the relocation and scratch init
work, we should have an atomic lottery to decide which HART does
the relocation and scratch init.

This way any HART can be boot/main HART.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>