drm/msm: Remove pm_runtime calls from msm_iommu.c

drm/msm: Remove pm_runtime calls from msm_iommu.c

Currently the IOMMU code calls pm_runtime_get/put on the GPU or display
device before doing a IOMMU operation. This was because usually the
IOMMU driver didn't do power control of its own and since the hardware
used the same clocks and power as the respective multimedia device it
was a easy way to make sure that the power was available.

Now two things have changed. First, the SMMU devices can do their own power
control and more important bringing up the a6xx GPU isn't as easy as
turning on some clocks. To bring the GPU up we need the GMU which itself
needs the IOMMU so we have a chicken and egg problem.

Luckily this is easily fixed by removing the pm_runtime calls from the
functions and letting the device link to the IOMMU device handle the magic.

Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Tested-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Rob Clark <robdclark@chromium.org>