trivial: Show the interface size for an invalid DFU device
trivial: Show the interface size for an invalid DFU device

fwupd/fwupd,fwupd/fwupd,hughsie/fwupd,superm1/fwupd,superm1/fwupd,vathpela/fwupd,vathpela/fwupd,vathpela/fwupd,fwupd/fwupd,hughsie/fwupd,superm1/fwupd,fwupd/fwupd,hughsie/fwupd,vathpela/fwupd,hughsie/fwupd