omap-serial: Allow IXON and IXOFF to be disabled.

Fixes logic bug that software flow control cannot be disabled, because
serial_omap_configure_xonxoff() is not called if both IXON and IXOFF bits
are cleared.
Signed-off-by: Nick Pelly <npelly@google.com>
Acked-by: Govindraj.R <govindraj.raja@ti.com>
Tested-by: Govindraj.R <govindraj.raja@ti.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/tty/serial/omap-serial.c

@@ -806,8 +806,7 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
 
 	serial_omap_set_mctrl(&up->port, up->port.mctrl);
 	/* Software Flow Control Configuration */
-	if (termios->c_iflag & (IXON | IXOFF))
-		serial_omap_configure_xonxoff(up, termios);
+	serial_omap_configure_xonxoff(up, termios);
 
 	spin_unlock_irqrestore(&up->port.lock, flags);
 	dev_dbg(up->port.dev, "serial_omap_set_termios+%d\n", up->pdev->id);