esp32_serial.c: Don't fake an interrupt when interrupts are not

suppressed.

Signed-off-by: Abdelatif Guettouche <abdelatif.guettouche@espressif.com>

arch/xtensa/src/esp32/esp32_serial.c

@@ -1726,6 +1726,7 @@ static void esp32_txint(struct uart_dev_s *dev, bool enable)
           modifyreg32(UART_INT_ENA_REG(priv->config->id),
                       0, (UART_TX_DONE_INT_ENA | UART_TXFIFO_EMPTY_INT_ENA));
 
+    #else
           /* Fake a TX interrupt here by just calling uart_xmitchars() with
            * interrupts disabled (note this may recurse).
            */