msm: kgsl: Program both IOMMUs at our disposal on 8064

APQ8064 has two AXI ports attached to the GPU with an IOMMU on both.
The VBIF can be programmed to use a round-robin arbitration to access
the ports equally, so we need to program both IOMMUs with the same
pagetable to make sure that the GPU can get where it needs to go.
All this involves a board file infrastructure change that affects 8960
too, but no functional changes are happening for that platform.

Change-Id: Ic0dedbad5198ed9c453711e58a3f1220ef5d5b4e
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>