msm: clock-8960: Add core clock for second gfx3d iommu on 8960ab

The 8960ab has two gfx3d iommus one of which was missing.
Also add a dependency on gfx3d_axi_clk for 8960ab.

Change-Id: If11e6e5e6d860f27db94b6633d44b94d0ce56ed2
Signed-off-by: Joel King <joelking@codeaurora.org>