iommu/arm-smmu-qcom: Fix TTBR0 read

It is a 64b register, lets not lose the upper bits.

Fixes: ab5df7b9 ("iommu/arm-smmu-qcom: Add an adreno-smmu-priv callback to get pagefault info")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211108171724.470973-1-robdclark@gmail.com


Signed-off-by: Will Deacon <will@kernel.org>