iommu/amd: Remove unused struct fault.devid

This variable has not been used since it was introduced.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Link: https://lore.kernel.org/r/20220301085626.87680-5-vasant.hegde@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>