iommu: Fix error unwind in iommu_group_alloc()

iommu: Fix error unwind in iommu_group_alloc()

If either iommu_group_grate_file() fails then the
iommu_group is leaked.

Destroy it on these error paths.

Found by kselftest/iommu/iommufd_fail_nth

Fixes: bc7d12b91bd3 ("iommu: Implement reserved_regions iommu-group sysfs file")
Fixes: c52c72d3dee8 ("iommu: Add sysfs attribyte for domain type")
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/0-v1-8f616bee028d+8b-iommu_group_alloc_leak_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>