msm: kgsl Fix stack exception occurring during axi error

When an axi error happens and the GPU is using IOMMU then a warning stack
trace was being reported. This is because during axi error interrupt
handling the IOMMU clocks were being turned on to read the current
pagetable base address. Switching the IOMMU clocks from interrupt context
is not allowed. Fix this by reporting the axi error and displaying 0
as the pagetable base address since we cannot read its value from
the axi error interrupt code.

Change-Id: If98538bc1b2df51a1b3632faf449d5d332bccc3e
Signed-off-by: Shubhraprakash Das <sadas@codeaurora.org>