iommu/arm-smmu-qcom: Make set_stall work when the device is on

Up until now we have only called the set_stall callback during
initialization when the device is off. But we will soon start calling it
to temporarily disable stall-on-fault when the device is on, so handle
that by checking if the device is on and writing SCTLR.

Signed-off-by: Connor Abbott <cwabbott0@gmail.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Link: https://lore.kernel.org/r/20250520-msm-gpu-fault-fixes-next-v8-3-fce6ee218787@gmail.com


[will: Fix "mixed declarations and code" warning from sparse]
Signed-off-by: Will Deacon <will@kernel.org>