msm: kgsl: Move VBIF register programming to device start

In Content Protection trustzone restricts access to all VBIF registers
till GPU driver attaches a pagetable to any IOMMU context bank.
Trying to access VBIF registers before pagetable attach causes
XPU violations on these targets. During device initialization move
all VBIF register access after pagetable attach.

Change-Id: I5e7b1351b5c094668616027c7cd3432ff565a2df
Signed-off-by: Tarun Karra <tkarra@codeaurora.org>