msm: kgsl: store DOMAIN_ATTR_PT_BASE_ADDR value in the pagetable

We need to use this value in the iommu fault handler so
calling iommu_domain_get_attr() to look it up at that time
risks lock recursion in the iommu driver. Instead,
query this attribute once and keep the result.

Change-Id: Iaa8f676ef37a177936927780b077d7192d4f6ded
Signed-off-by: Jeremy Gebben <jgebben@codeaurora.org>