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/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index 6af145f..3580f19 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -512,7 +512,7 @@
 		req = list_first_entry(queue, struct usb_request, list);
 
 		/* leave data queued if tty was rx throttled */
-		if (tty && test_bit(TTY_THROTTLED, &tty->flags))
+		if (tty && tty_throttled(tty))
 			break;
 
 		switch (req->status) {
@@ -579,7 +579,7 @@
 	 * from starving ... but it's not clear that case ever happens.
 	 */
 	if (!list_empty(queue) && tty) {
-		if (!test_bit(TTY_THROTTLED, &tty->flags)) {
+		if (!tty_throttled(tty)) {
 			if (do_push)
 				tasklet_schedule(&port->push);
 			else