ARM: dts: msm: Introduce bus topology for msmzirc

Bus scaling driver allows clients to make bandwidth requests between end
points. The bus topology allows bus scaling driver to honor these requests
by representing in software the device connections.

Change-Id: I281a58259e4a09eab49bc796975c17d36ad4192d
Signed-off-by: Girish Mahadevan <girishm@codeaurora.org>