USB: serial: fix console error reporting

Do not report errors in write path if port is used as a console as this
may trigger the same error (and error report) resulting in a loop.

Reported-by: Stephen Hemminger <[e-mail]>
Cc: stable <[e-mail]>
Signed-off-by: Johan Hovold <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/serial/generic.c

···
 	clear_bit(i, &port->write_urbs_free);
 	result = usb_submit_urb(urb, GFP_ATOMIC);
 	if (result) {
-		dev_err(&port->dev, "%s - error submitting urb: %d\n",
+		if (!port->port.console) {
+			dev_err(&port->dev, "%s - error submitting urb: %d\n",
 						__func__, result);
+		}
 		set_bit(i, &port->write_urbs_free);
 		spin_lock_irqsave(&port->lock, flags);
 		port->tx_bytes -= count;