ARM: dts: qcom: Add bus scale voting info for 8996

On 8996, bus scale voting is required for proper operation of all
multimedia SMMUs (everything behind mmagic).  Add the necessary
configuration information for the relevant SMMUs.

Change-Id: I644b29b8c761e126ec96cf4176220e218f21bcbe
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>