TTY: switch tty_flip_buffer_push

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.

Now, the one where most of tty_port_tty_get gets removed:
tty_flip_buffer_push.

IOW we also closed all the races in drivers not using tty_port_tty_get
at all yet.

Also we move tty_flip_buffer_push declaration from include/linux/tty.h
to include/linux/tty_flip.h to all others while we are changing it
anyway.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index 00047f3..54adc91 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -772,7 +772,6 @@
 {
 	struct usb_serial_port *port = urb->context;
 	struct pl2303_private *priv = usb_get_serial_port_data(port);
-	struct tty_struct *tty;
 	unsigned char *data = urb->transfer_buffer;
 	char tty_flag = TTY_NORMAL;
 	unsigned long flags;
@@ -789,10 +788,6 @@
 	if (!urb->actual_length)
 		return;
 
-	tty = tty_port_tty_get(&port->port);
-	if (!tty)
-		return;
-
 	/* break takes precedence over parity, */
 	/* which takes precedence over framing errors */
 	if (line_status & UART_BREAK_ERROR)
@@ -817,8 +812,7 @@
 							urb->actual_length);
 	}
 
-	tty_flip_buffer_push(tty);
-	tty_kref_put(tty);
+	tty_flip_buffer_push(&port->port);
 }
 
 /* All of the device info needed for the PL2303 SIO serial converter */