iommu: Always destroy the iommu_group during iommu_release_device()

Have release fully clean up the iommu related parts of the struct device,
no matter what state they are in.

Split the logic so that the three things owned by the iommu core are
always cleaned up:
 - Any attached iommu_group
 - Any allocated dev->iommu and its contents including a fwsepc
 - Any attached driver via a struct group_device

This fixes a minor bug where a fwspec created without an iommu_group being
probed would not be freed.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/8-v3-328044aa278c+45e49-iommu_probe_jgg@nvidia.com


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