Move the RSE MHU channel initialization to the platform setup phase,
this allows the services (e.g. TRNG service) to talk to RSE during the
service init function.
Change-Id: Id0ff6e49117008463f11b2dc3c585daca00f609c
Signed-off-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: Icen Zeyada <Icen.Zeyada2@arm.com>