`efivar` dependency not needed anymore
The same commit that dropped plugin_dell and libsmbios also dropped the need for efivar
https://github.com/fwupd/fwupd/commit/c01f7adfb3db56bcbe517eda8820c20480d1f2f1
Fwupd has internal NVRAM variable handling now and there is no need for this explicit dependency.