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/oti6858.c b/drivers/usb/serial/oti6858.c
index d217fd6..7a53fe9 100644
--- a/drivers/usb/serial/oti6858.c
+++ b/drivers/usb/serial/oti6858.c
@@ -837,7 +837,7 @@
 
 	tty = tty_port_tty_get(&port->port);
 	if (tty != NULL && urb->actual_length > 0) {
-		tty_insert_flip_string(tty, data, urb->actual_length);
+		tty_insert_flip_string(&port->port, data, urb->actual_length);
 		tty_flip_buffer_push(tty);
 	}
 	tty_kref_put(tty);