co2_sensor: Replace (if + switch) with switch.

ampel-firmware/co2_sensor.cpp

@@ -204,8 +204,8 @@ namespace sensor {
     case BOOTUP:
       led_effects::showWaitingLED(color::blue);
       break;
-      // No special signaling, we want to show the CO2 value
     case READY:
+      displayCO2OnLedRing();
       break;
     case NEEDS_CALIBRATION:
       led_effects::showWaitingLED(color::magenta);
@@ -261,12 +261,7 @@ namespace sensor {
       logToSerial();
     }
 
-    // We need to show LED effects for "old" data, too, as long as we get new data.
-    if (current_state == READY) {
-      displayCO2OnLedRing();
-    } else {
-      showState();
-    }
+    showState();
 
     return freshData;
   }