soc: qcom: scm: Restructure Milestone call

Moving milestone to soc specific early initcall. This change
is to enable kernel memory protection before multi-core bring
up, to avoid a race condition between cores.

Change-Id: Iaeb6620ed1f5bb89265a2529d15cfbde50a829ee
Acked-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Preeti Nagar <pnagar@codeaurora.org>