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>

drivers/tty/serial/ucc_uart.c

@@ -470,7 +470,6 @@ static void qe_uart_int_rx(struct uart_qe_port *qe_port)
 	unsigned char ch, *cp;
 	struct uart_port *port = &qe_port->port;
 	struct tty_port *tport = &port->state->port;
-	struct tty_struct *tty = tport->tty;
 	struct qe_bd *bdp;
 	u16 status;
 	unsigned int flg;
@@ -531,7 +530,7 @@ error_return:
 	qe_port->rx_cur = bdp;
 
 	/* Activate BH processing */
-	tty_flip_buffer_push(tty);
+	tty_flip_buffer_push(tport);
 
 	return;