iommu/mediatek: Add a PM_CLK_AO flag for infra iommu

The power/clock of infra iommu is always on, and it doesn't have the
device link with the master devices, then the infra iommu device's PM
status is not active, thus we add A PM_CLK_AO flag for infra iommu.

The tlb operation is a bit not clear here, there are 2 special cases.
Comment them in the code.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/r/20220503071427.2285-21-yong.wu@mediatek.com


Signed-off-by: Joerg Roedel <jroedel@suse.de>