msm: iommu: Remove the vcap iommu from 8960ab.

There is no vcap iommu in the 8960ab platform.
Also, a cleaner separation between platforms is
obtained by re-organizing the gfx3d and vcap
structures by device block instead of by msm.

Signed-off-by: Joel King <joelking@codeaurora.org>
(cherry picked from commit b82921f4)

Change-Id: I044842db17a59f6df1328674a5d65931313dead2
Signed-off-by: Sudhir Sharma <sudsha@codeaurora.org>