intel: Extend SiP service to support mailbox's RSU

Introduce support for RSU that can be initiated through SMC calls.

Added features as below:
- RSU status
- RSU update
- RSU HPS notify
- RSU get sub-partition

Signed-off-by: Hadi Asyrafi <muhammad.hadi.asyrafi.abdul.halim@intel.com>
Change-Id: I78d5a07688e43da99f03d77dfd45ffb4a78f2e4c
6 files changed