arm/dt: iommu: Add bus bw voting to IOMMUv0 nodes

Add bus voting data to IOMMUv0 nodes allowing IOMMU driver to
vote for bus bandwidth when the IOMMU is being used. This is
required for certain clocks to turn on.

Change-Id: I0b6cf7533d3a35348e9866359fb84c124677e8d4
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>