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/usb/serial/omninet.c b/drivers/usb/serial/omninet.c
index 338191b..1e1cafe 100644
--- a/drivers/usb/serial/omninet.c
+++ b/drivers/usb/serial/omninet.c
@@ -174,14 +174,9 @@
 	}
 
 	if (urb->actual_length && header->oh_len) {
-		struct tty_struct *tty = tty_port_tty_get(&port->port);
-		if (tty) {
-			tty_insert_flip_string(&port->port,
-					data + OMNINET_DATAOFFSET,
-					header->oh_len);
-			tty_flip_buffer_push(tty);
-			tty_kref_put(tty);
-		}
+		tty_insert_flip_string(&port->port, data + OMNINET_DATAOFFSET,
+				header->oh_len);
+		tty_flip_buffer_push(&port->port);
 	}
 
 	/* Continue trying to always read  */