iommu/arm-smmu: Make remove callback message more informative

Currently on reboot/shutdown, the following messages are
displayed on the console as error messages before the
system reboots/shutdown as part of remove callback.

On SC7180:

  arm-smmu 15000000.iommu: removing device with active domains!
  arm-smmu 5040000.iommu: removing device with active domains!

Make this error message more informative and less scary.

Reported-by: Douglas Anderson <dianders@chromium.org>
Suggested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20200423095531.9868-1-saiprakash.ranjan@codeaurora.org


[will: use dev_notice() as per Robin]
Signed-off-by: Will Deacon <will@kernel.org>