trivial: redfish: drop unused import and variables
trivial: redfish: drop unused import and variables

found by codacity

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