trivial: Fix a tiny memory leak introduced with the UPower fix
trivial: Fix a tiny memory leak introduced with the UPower fix

fwupd/fwupd,hughsie/fwupd,hughsie/fwupd,hughsie/fwupd,fwupd/fwupd,hughsie/fwupd,fwupd/fwupd,fwupd/fwupd