vfio/iommufd: Remove CONFIG_IOMMUFD usage Availability of the IOMMUFD backend can now be fully determined at runtime and the ifdef check was a build time protection (for PPC not supporting it mostly). Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com> Tested-by: Eric Farman <farman@linux.ibm.com> Signed-off-by: Cédric Le Goater <clg@redhat.com>