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/tty/serial/mpc52xx_uart.c b/drivers/tty/serial/mpc52xx_uart.c
index 0145aeb..c0e1fad 100644
--- a/drivers/tty/serial/mpc52xx_uart.c
+++ b/drivers/tty/serial/mpc52xx_uart.c
@@ -942,7 +942,6 @@
 mpc52xx_uart_int_rx_chars(struct uart_port *port)
 {
 	struct tty_port *tport = &port->state->port;
-	struct tty_struct *tty = tport->tty;
 	unsigned char ch, flag;
 	unsigned short status;
 
@@ -1000,7 +999,7 @@
 	}
 
 	spin_unlock(&port->lock);
-	tty_flip_buffer_push(tty);
+	tty_flip_buffer_push(tport);
 	spin_lock(&port->lock);
 
 	return psc_ops->raw_rx_rdy(port);