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/mux.c b/drivers/tty/serial/mux.c
index 83b2168..7fd6aaa 100644
--- a/drivers/tty/serial/mux.c
+++ b/drivers/tty/serial/mux.c
@@ -244,7 +244,6 @@
 {
 	struct tty_port *tport = &port->state->port;
 	int data;
-	struct tty_struct *tty = tport->tty;
 	__u32 start_count = port->icount.rx;
 
 	while(1) {
@@ -270,9 +269,8 @@
 		tty_insert_flip_char(tport, data & 0xFF, TTY_NORMAL);
 	}
 	
-	if (start_count != port->icount.rx) {
-		tty_flip_buffer_push(tty);
-	}
+	if (start_count != port->icount.rx)
+		tty_flip_buffer_push(tport);
 }
 
 /**