Always call update_use_power() instead of directly setting the use_power var.

- This will let us react to the change appropriately.
- While we're here, lets define some constants so we can stop using bare numbers.
- Always use those constants when calling update_use_power()

code/modules/modular_computers/NTNet/NTNet_relay.dm

@@ -38,9 +38,9 @@
 
 /obj/machinery/ntnet_relay/process()
 	if(operable())
-		use_power = 2
+		update_use_power(USE_POWER_ACTIVE)
 	else
-		use_power = 1
+		update_use_power(USE_POWER_IDLE)
 
 	if(dos_overload)
 		dos_overload = max(0, dos_overload - dos_dissipate)