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/safe_serial.c b/drivers/usb/serial/safe_serial.c
index c949ce6..ad12e9e 100644
--- a/drivers/usb/serial/safe_serial.c
+++ b/drivers/usb/serial/safe_serial.c
@@ -235,7 +235,7 @@
 	dev_info(&urb->dev->dev, "%s - actual: %d\n", __func__, actual_length);
 	length = actual_length;
 out:
-	tty_insert_flip_string(tty, data, length);
+	tty_insert_flip_string(&port->port, data, length);
 	tty_flip_buffer_push(tty);
 err:
 	tty_kref_put(tty);