fwupdtool uses udisks2 to setup access to ESP partition.
udisks2 depends on polkit feature so make the dependency
conditional in fwupd too. The dependency is not needed
for all usecases.
Signed-off-by: Mikko Rapeli <mikko.rapeli@linaro.org>
Signed-off-by: Khem Raj <raj.khem@gmail.com>