tty: serial: qcom-geni-serial: stop operations in progress at shutdown

We don't stop transmissions in progress at shutdown. This is fine with
FIFO SE mode but with DMA (support for which we'll introduce later) it
causes trouble so fix it now.

Fixes: e837663 ("tty: serial: qcom_geni_serial: No need to stop tx/rx on UART shutdown")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20221229155030.418800-2-brgl@bgdev.pl
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Bartosz Golaszewski

drivers/tty/serial/qcom_geni_serial.c

@@ -880,6 +880,8 @@ static void get_tx_fifo_size(struct qcom_geni_serial_port *port)
 static void qcom_geni_serial_shutdown(struct uart_port *uport)
 {
 	disable_irq(uport->irq);
+	qcom_geni_serial_stop_tx(uport);
+	qcom_geni_serial_stop_rx(uport);
 }
 
 static int qcom_geni_serial_port_setup(struct uart_port *uport)