TTY: switch tty_insert_flip_string

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

tty_insert_flip_string this time.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/serial/quatech2.c b/drivers/usb/serial/quatech2.c
index 1e67fd8..5dccc4f 100644
--- a/drivers/usb/serial/quatech2.c
+++ b/drivers/usb/serial/quatech2.c
@@ -698,7 +698,7 @@
 				break;
 			case QT2_CONTROL_ESCAPE:
 				tty_buffer_request_room(&port->port, 2);
-				tty_insert_flip_string(tty, ch, 2);
+				tty_insert_flip_string(&port->port, ch, 2);
 				i += 2;
 				escapeflag = true;
 				break;
@@ -712,10 +712,8 @@
 				continue;
 		}
 
-		if (tty) {
-			tty_buffer_request_room(&port->port, 1);
-			tty_insert_flip_string(tty, ch, 1);
-		}
+		tty_buffer_request_room(&port->port, 1);
+		tty_insert_flip_string(&port->port, ch, 1);
 	}
 
 	if (tty) {