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>

drivers/tty/serial/jsm/jsm_tty.c

@@ -654,7 +654,7 @@ void jsm_input(struct jsm_channel *ch)
 	spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
 
 	/* Tell the tty layer its okay to "eat" the data now */
-	tty_flip_buffer_push(tp);
+	tty_flip_buffer_push(port);
 
 	jsm_dbg(IOCTL, &ch->ch_bd->pci_dev, "finish\n");
 }