feat(interrupts): introduce a new paravirtualized interface

This patch adds basic support for a new paravirtualized interface that
allows an SP to reconfigure an interrupt, it owns, in runtime. Further
patches will add the complete support.

Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
Change-Id: I45ad89d177da3303fc413f250e44e4c1ca1bf9dc
4 files changed