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/clps711x.c b/drivers/tty/serial/clps711x.c
index 3fd2526..bfb1796 100644
--- a/drivers/tty/serial/clps711x.c
+++ b/drivers/tty/serial/clps711x.c
@@ -85,12 +85,8 @@
 static irqreturn_t uart_clps711x_int_rx(int irq, void *dev_id)
 {
 	struct uart_port *port = dev_id;
-	struct tty_struct *tty = tty_port_tty_get(&port->state->port);
 	unsigned int status, ch, flg;
 
-	if (!tty)
-		return IRQ_HANDLED;
-
 	for (;;) {
 		status = clps_readl(SYSFLG(port));
 		if (status & SYSFLG_URXFE)
@@ -130,9 +126,7 @@
 		uart_insert_char(port, status, UARTDR_OVERR, ch, flg);
 	}
 
-	tty_flip_buffer_push(tty);
-
-	tty_kref_put(tty);
+	tty_flip_buffer_push(&port->state->port);
 
 	return IRQ_HANDLED;
 }