trivial: Fix up some missing return value assignments
trivial: Fix up some missing return value assignments

Spotted by coverity.

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