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/max310x.c b/drivers/tty/serial/max310x.c
index a801f68..0c2422c 100644
--- a/drivers/tty/serial/max310x.c
+++ b/drivers/tty/serial/max310x.c
@@ -460,10 +460,6 @@
 static void max310x_handle_rx(struct max310x_port *s, unsigned int rxlen)
 {
 	unsigned int sts = 0, ch = 0, flag;
-	struct tty_struct *tty = tty_port_tty_get(&s->port.state->port);
-
-	if (!tty)
-		return;
 
 	if (unlikely(rxlen >= MAX310X_FIFO_SIZE)) {
 		dev_warn(s->port.dev, "Possible RX FIFO overrun %d\n", rxlen);
@@ -516,9 +512,7 @@
 				 ch, flag);
 	}
 
-	tty_flip_buffer_push(tty);
-
-	tty_kref_put(tty);
+	tty_flip_buffer_push(&s->port.state->port);
 }
 
 static void max310x_handle_tx(struct max310x_port *s)