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/hvc/hvsi.c b/drivers/tty/hvc/hvsi.c
index 1f528b8..dc59129 100644
--- a/drivers/tty/hvc/hvsi.c
+++ b/drivers/tty/hvc/hvsi.c
@@ -465,7 +465,7 @@
 	compact_inbuf(hp, packet);
 
 	if (flip)
-		tty_flip_buffer_push(tty);
+		tty_flip_buffer_push(&hp->port);
 
 	return 1;
 }
@@ -511,7 +511,7 @@
 		/* we weren't hung up and we weren't throttled, so we can
 		 * deliver the rest now */
 		hvsi_send_overflow(hp);
-		tty_flip_buffer_push(tty);
+		tty_flip_buffer_push(&hp->port);
 	}
 	spin_unlock_irqrestore(&hp->lock, flags);
 
@@ -998,7 +998,7 @@
 	spin_lock_irqsave(&hp->lock, flags);
 	if (hp->n_throttle) {
 		hvsi_send_overflow(hp);
-		tty_flip_buffer_push(tty);
+		tty_flip_buffer_push(&hp->port);
 	}
 	spin_unlock_irqrestore(&hp->lock, flags);