LEDControl: Fix a thinko in FocusLEDCommand

When handling the `led.brightness` command, we forgot to break out of the switch
statement, thus executing the `setall` branch too. This resulted in very slow
operations, because we had to wait for a read to timeout.

Adding a break fixes all that.

Signed-off-by: Gergely Nagy <algernon@keyboard.io>

src/kaleidoscope/plugin/LEDControl.cpp

@@ -245,6 +245,7 @@ EventHandlerResult FocusLEDCommand::onFocusEvent(const char *command) {
       ::Focus.read(brightness);
       ::LEDControl.setBrightness(brightness);
     }
+    break;
   }
   case SETALL: {
     cRGB c;