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/pnx8xxx_uart.c b/drivers/tty/serial/pnx8xxx_uart.c
index 0aa75a9..7e277a5 100644
--- a/drivers/tty/serial/pnx8xxx_uart.c
+++ b/drivers/tty/serial/pnx8xxx_uart.c
@@ -181,7 +181,6 @@
 
 static void pnx8xxx_rx_chars(struct pnx8xxx_port *sport)
 {
-	struct tty_struct *tty = sport->port.state->port.tty;
 	unsigned int status, ch, flg;
 
 	status = FIFO_TO_SM(serial_in(sport, PNX8XXX_FIFO)) |
@@ -238,7 +237,7 @@
 		status = FIFO_TO_SM(serial_in(sport, PNX8XXX_FIFO)) |
 			 ISTAT_TO_SM(serial_in(sport, PNX8XXX_ISTAT));
 	}
-	tty_flip_buffer_push(tty);
+	tty_flip_buffer_push(&sport->port.state->port);
 }
 
 static void pnx8xxx_tx_chars(struct pnx8xxx_port *sport)