iommu/tegra-smmu: Prune IOMMU group when it is released

In order to share groups between multiple devices we keep track of them
in a per-SMMU list. When an IOMMU group is released, a dangling pointer
to it stays around in that list. Fix this by implementing an IOMMU data
release callback for groups where the dangling pointer can be removed.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20200806155404.3936074-4-thierry.reding@gmail.com


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