msm: mdss: featurize bus bandwidth vote required during IOMMU attach

On certain chipsets, MDSS need to have SYS_MM_NOC clock enabled to be
able to perform IOMMU transactions. IOMMU driver will not vote for
bandwidth since it is tied to SYS_NOC and not SYS_MM_NOC. This needs
some minimum bandwidth vote from MDSS side. Add a DT property to enable
featurization of this.

Change-Id: I4b6b2b946080019f3f803c96c7a1b31759aa9020
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>