haven: add stubs to haven client exposed APIs

There are Non-VM (Virtual Machine) supported target drivers which
may refer some of the APIs defined for VMs. But those drivers are
compiled irrespective of VM or non-VM configurations. Add stubs to
support to compile drivers for non vm supported targets.

Change-Id: Ibc0c2c55b3b264c43c4793f153e723f8d344423a
Signed-off-by: Murali Nalajala <mnalajal@codeaurora.org>