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>

arch/parisc/kernel/pdc_cons.c

@@ -138,10 +138,6 @@ static const struct tty_operations pdc_console_tty_ops = {
 static void pdc_console_poll(unsigned long unused)
 {
 	int data, count = 0;
-	struct tty_struct *tty = tty_port_tty_get(&tty_port);
-
-	if (!tty)
-		return;
 
 	while (1) {
 		data = pdc_console_poll_key(NULL);
@@ -152,9 +148,7 @@ static void pdc_console_poll(unsigned long unused)
 	}
 
 	if (count)
-		tty_flip_buffer_push(tty);
-
-	tty_kref_put(tty);
+		tty_flip_buffer_push(&tty_port);
 
 	if (pdc_cons.flags & CON_ENABLED)
 		mod_timer(&pdc_console_timer, jiffies + PDC_CONS_POLL_DELAY);