soc: qcom: mem-buf: Add support for inter-VM memory sharing

Add the initial support required to share memory buffers
between VMs. This driver exposes an interface to userspace
clients to request memory to be allocated from another VM,
and added to the current VM. The VMs communicate with each
other via the use of the hypervisor message queues, as well
as utilize various facilities offered by the Haven resource
manager to manage memory that is transferred from one VM
to another.

Change-Id: I3181a1b14e61db30ed6b86752750722e24fd62e0
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>