tty: serial: 8250_core: remove UART_IER_RDI in serial8250_stop_rx()

serial8250_do_startup() adds UART_IER_RDI and UART_IER_RLSI to ier.
serial8250_stop_rx() should remove both.
This is what the serial-omap driver has been doing and is now moved to
the 8250-core since it does no look to be *that* omap specific.

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_core.c

@@ -1390,7 +1390,7 @@ static void serial8250_stop_rx(struct uart_port *port)
 
 	serial8250_rpm_get(up);
 
-	up->ier &= ~UART_IER_RLSI;
+	up->ier &= ~(UART_IER_RLSI | UART_IER_RDI);
 	up->port.read_status_mask &= ~UART_LSR_DR;
 	serial_port_out(port, UART_IER, up->ier);