feat(rme): add RMM dispatcher (RMMD)

This patch introduces the RMM dispatcher into BL31. This
will be the mechanism that will enable communication to
take place between the Realm and non-secure world. Currently
gives the capability for granules to be
transitioned from non-secure type to realm and vice versa.

Signed-off-by: Zelalem Aweke <zelalem.aweke@arm.com>
Signed-off-by: Subhasish Ghosh <subhasish.ghosh@arm.com>
Change-Id: I1fdc99a4bdd42bc14911aa0c6954b131de309511
12 files changed