iommu/mediatek: Always tlb_flush_all when each PM resume

Prepare for 2 HWs that sharing pgtable in different power-domains.

When there are 2 M4U HWs, it may has problem in the flush_range in which
we get the pm_status via the m4u dev, BUT that function don't reflect the
real power-domain status of the HW since there may be other HW also use
that power-domain.

DAM allocation is often done while the allocating device is runtime
suspended. In such a case the iommu will also be suspended and partial
flushing of the tlb will not be executed.
Therefore, we add a tlb_flush_all in the pm_runtime_resume to make
sure the tlb is always clean.

In other case, the iommu's power should be active via device
link with smi.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
[move the call to mtk_iommu_tlb_flush_all to the bottom of resume cb, improve doc/log]
Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20211208120744.2415-6-dafna.hirschfeld@collabora.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>