Reduces the effect of EMP on robot power cells

Temporary fix to resolve #8454

code/modules/power/cell.dm

@@ -128,6 +128,11 @@
 		rigged = 1 //broken batterys are dangerous
 
 /obj/item/weapon/cell/emp_act(severity)
+	//remove this once emp changes on dev are merged in
+	if(isrobot(loc))
+        var/mob/living/silicon/robot/R = loc
+        severity *= R.cell_emp_mult
+
 	charge -= maxcharge / severity
 	if (charge < 0)
 		charge = 0