Removes all the hard references to computer.dmi

I assume these were all lazy copy-pasting. We're changing computer icons to another set in a file we'll keep separate, and these completely pointless references are annoying. They should inherit this from the `/computer/` level, which they do. Has no effect on Polaris, but cleans up code that shouldn't exist.

code/modules/mob/living/silicon/robot/drone/drone_console.dm

@@ -1,7 +1,6 @@
 /obj/machinery/computer/drone_control
 	name = "Maintenance Drone Control"
 	desc = "Used to monitor the station's drone population and the assembler that services them."
-	icon = 'icons/obj/computer.dmi'
 	icon_keyboard = "power_key"
 	icon_screen = "power"
 	req_access = list(access_engine_equip)

code/modules/power/gravitygenerator.dm

@@ -3,7 +3,6 @@
 /obj/machinery/computer/gravity_control_computer
 	name = "Gravity Generator Control"
 	desc = "A computer to control a local gravity generator.  Qualified personnel only."
-	icon = 'icons/obj/computer.dmi'
 	icon_state = "airtunnel0e"
 	anchored = 1
 	density = 1

code/modules/power/sensors/sensor_monitoring.dm

@@ -6,7 +6,6 @@
 /obj/machinery/computer/power_monitor
 	name = "Power Monitoring Console"
 	desc = "Computer designed to remotely monitor power levels around the station"
-	icon = 'icons/obj/computer.dmi'
 	icon_keyboard = "power_key"
 	icon_screen = "power:0"
 	light_color = "#ffcc33"

code/modules/power/turbine.dm

@@ -28,7 +28,6 @@
 /obj/machinery/computer/turbine_computer
 	name = "Gas turbine control computer"
 	desc = "A computer to remotely control a gas turbine"
-	icon = 'icons/obj/computer.dmi'
 	icon_keyboard = "tech_key"
 	icon_screen = "turbinecomp"
 	circuit = /obj/item/weapon/circuitboard/turbine_control

code/modules/shuttles/shuttle_console.dm

@@ -1,6 +1,5 @@
 /obj/machinery/computer/shuttle_control
 	name = "shuttle control console"
-	icon = 'icons/obj/computer.dmi'
 	icon_keyboard = "atmos_key"
 	icon_screen = "shuttle"
 	circuit = null

code/modules/virus2/curer.dm

@@ -1,6 +1,5 @@
 /obj/machinery/computer/curer
 	name = "cure research machine"
-	icon = 'icons/obj/computer.dmi'
 	icon_keyboard = "med_key"
 	icon_screen = "dna"
 	circuit = /obj/item/weapon/circuitboard/curefab

code/modules/virus2/diseasesplicer.dm

@@ -1,6 +1,5 @@
 /obj/machinery/computer/diseasesplicer
 	name = "disease splicer"
-	icon = 'icons/obj/computer.dmi'
 	icon_keyboard = "med_key"
 	icon_screen = "crew"