TTY: add tty_port_tty_wakeup helper

It allows for cleaning up on a considerable amount of places. They did
port_get, wakeup, kref_put. Now the only thing needed is to call
tty_port_tty_wakeup which does exactly that.

One exception is ifx6x60 where tty_wakeup was open-coded. We now call
tty_wakeup properly there.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index f1b3857..cc206ed 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -248,7 +248,6 @@
 {
 	struct chan *chan = data;
 	struct line *line = chan->line;
-	struct tty_struct *tty;
 	int err;
 
 	/*
@@ -267,12 +266,7 @@
 	}
 	spin_unlock(&line->lock);
 
-	tty = tty_port_tty_get(&line->port);
-	if (tty == NULL)
-		return IRQ_NONE;
-
-	tty_wakeup(tty);
-	tty_kref_put(tty);
+	tty_port_tty_wakeup(&line->port);
 
 	return IRQ_HANDLED;
 }