trivial: Fix build warning when compiling 'make check'
trivial: Fix build warning when compiling 'make check'

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