fix: warning unused var

Signed-off-by: Dimitar Atanasov <datanasov@cpdbg.com>

razer_control_gui/src/device.rs

@@ -410,7 +410,7 @@ impl DeviceManager {
         return 0;
     }
 
-    pub fn get_power_mode(&mut self, ac:usize) -> u8 {
+    pub fn get_power_mode(&mut self, _ac:usize) -> u8 {
         if let Some(laptop) = self.get_device() {
             return laptop.get_power_mode(0x01);
         }