graphics: display: set default power to 500mA

src/graphics/display.rs

@@ -178,7 +178,8 @@ impl Default for ControlData {
             on: AtomicBool::new(true),
             brightness: AtomicU8::new(255),
             fps: AtomicU8::new(DEFAULT_FPS),
-            max_power_mw: AtomicU32::new(0)
+            // We default to 500mA, because that's what we get over USB by default
+            max_power_mw: AtomicU32::new(500)
         }
     }
 }