Add devices in DFU mode
Add devices in DFU mode

By filtering out the devices not in runtime we have two problems:

* We can't use fwupdmgr to 'fix' any devices that failed to flash and are
  stuck in bootloader mode

* We can't transition from a runtime-less FuDevice to a DFU-capable FuDevice.

This allows the Nitrokey to be updated using fwupd.

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