Rebootless graphics switching

This changes out how the current graphics switching works, enabling
asusd to stop/start the display-manager to enable/disable PCI devices
and add/remove drivers as required.

All existing graphics modes and commands still work as normal.

G-Sync enable is now only through the bios setting, and on reboot
will set all relevant settings to Nvidia mode.

daemon/src/ctrl_fan_cpu.rs

@@ -8,7 +8,7 @@ use rog_types::profile::{FanLevel, ProfileEvent};
 use serde_derive::{Deserialize, Serialize};
 use std::convert::TryInto;
 use std::fs::OpenOptions;
-use std::io::{Read, Write};
+use std::io::Write;
 use std::path::Path;
 use std::sync::Arc;
 use std::sync::Mutex;