VCC/ADC: finish implementing VCC detection via ADC

... however, keep it disabled due to ADCVREF not being connected on
OWHWv1/v2.
diff --git a/firmware/include_board/owhw/board.h b/firmware/include_board/owhw/board.h
index 80529cf..ebfc618 100644
--- a/firmware/include_board/owhw/board.h
+++ b/firmware/include_board/owhw/board.h
@@ -45,5 +45,7 @@
 #define USB_PRODUCT_ID              SIMTRACE_PRODUCT_ID
 
 #define CARDEMU_SECOND_UART
+/* Disable VCC/ADC detection, as OWHWv2 has no ADCVREF */
+//#define DETECT_VCC_BY_ADC
 
 #define HAVE_CARDEM