msm: tspp2: Enable VBIF clocks properly

TSPP2 requires the VBIF AHB and AXI clocks to be enabled, even
when working in VBIF bypass mode.
VBIF clocks must be enabled before attaching IOMMU context bank and
disabled after detaching IOMMU context bank.

Change-Id: Id31e53aaa5367e7ae216c383e9d6dd055822c276
Signed-off-by: Liron Kuch <lkuch@codeaurora.org>