fix(uart): unused warnings

Fixes stm32duino#2718.

Signed-off-by: Frederic Pillon <[email protected]>

Author: fpistm

libraries/SrcWrapper/src/stm32/uart.c

@@ -438,6 +438,10 @@ bool uart_init(serial_t *obj, uint32_t baudrate, uint32_t databits, uint32_t par
     huart->AdvancedInit.DataInvert = UART_ADVFEATURE_DATAINV_ENABLE;
   }
 #endif
+#else /* UART_ADVFEATURE_NO_INIT */
+  UNUSED(rx_invert);
+  UNUSED(tx_invert);
+  UNUSED(data_invert);
 #endif
 #ifdef UART_ONE_BIT_SAMPLE_DISABLE
   huart->Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;