power-management: Don't enable acpid.
Running acpid along with systemd will cause double handling of acpi events.
Enable acpid if nvidia driver is being used.
The NVidia driver wants to connect to acpid to receive ACPI events.
Merge branch 'disable-acpid' of git://github.com/ambrop72/nixpkgs

power-management: Don't enable acpid.