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/isicom.c

@@ -637,7 +637,7 @@ static irqreturn_t isicom_interrupt(int irq, void *dev_id)
 			tty_insert_flip_char(&port->port, 0, TTY_BREAK);
 			if (port->port.flags & ASYNC_SAK)
 				do_SAK(tty);
-			tty_flip_buffer_push(tty);
+			tty_flip_buffer_push(&port->port);
 			break;
 
 		case 2:	/* Statistics		 */
@@ -671,7 +671,7 @@ static irqreturn_t isicom_interrupt(int irq, void *dev_id)
 				byte_count -= 2;
 			}
 		}
-		tty_flip_buffer_push(tty);
+		tty_flip_buffer_push(&port->port);
 	}
 	outw(0x0000, base+0x04); /* enable interrupts */
 	spin_unlock(&card->card_lock);