iommu/vt-d: Fix sysfs leak in alloc_iommu()

iommu_device_sysfs_add() is called before, so is has to be cleaned on subsequent
errors.

Fixes: 39ab9555 ("iommu: Add sysfs bindings for struct iommu_device")
Cc: stable@vger.kernel.org # 4.11.x
Signed-off-by: Rolf Eike Beer <eb@emlix.com>
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/17411490.HIIP88n32C@mobilepool36.emlix.com
Link: https://lore.kernel.org/r/20210525070802.361755-2-baolu.lu@linux.intel.com


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