net: ipc_router: Add support for IPC Router version negotiation

Currently, IPC Router statically associates the version of the
protocol to be used with each link. Thus, dynamic version negotiation
is not possible.

Add support for version negotiation that sets IPC Router version
after a successful negotiation.

Change-Id: Iea04742ef30443c1e36760561e7f20175c4fbaa6
Signed-off-by: Atish Kumar Patra <apatra@codeaurora.org>