tty: Replace TTY_THROTTLED bit tests with tty_throttled()

Abstract TTY_THROTTLED bit tests with tty_throttled().

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index 111d907..4b44586 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -2029,7 +2029,7 @@
 
 	tty = tty_port_tty_get(&serial->port);
 
-	if (tty && test_bit(TTY_THROTTLED, &tty->flags)) {
+	if (tty && tty_throttled(tty)) {
 		tty_kref_put(tty);
 		return -1;
 	}