Fix a logic error with testing for a dell system.
Fix a logic error with testing for a dell system.

Some Lenovo systems were inadvertently matching.

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