FROMLIST: gunyah: rsc_mgr: Add resource manager RPC core

The resource manager is a special virtual machine which is always
running on a Gunyah system. It provides APIs for creating and destroying
VMs, secure memory management, sharing/lending of memory between VMs,
and setup of inter-VM communication. Calls to the resource manager are
made via message queues.

This patch implements the basic probing and RPC mechanism to make those
API calls. Request/response calls can be made with gh_rm_call.
Drivers can also register to notifications pushed by RM via
gh_rm_register_notifier

Specific API calls that resource manager supports will be implemented in
subsequent patches.

Bug: 338347082
Link: https://lore.kernel.org/all/20240222-gunyah-v17-7-1e9da6763d38@quicinc.com/


Change-Id: I014020b676a4db46bd7d64cc62df4eda5259a1f3
Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>