USB: otg: Fix bug on remove path without transceiver

In the case where a gadget driver is removed while no
transceiver was found at probe time, a bug in
otg_put_transceiver() will trigger.

Provide symetric calls for otg_get_transceiver() and
otg_put_transceiver(), wherever a transceiver was found or
not.
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/otg/otg.c

@@ -43,7 +43,8 @@ EXPORT_SYMBOL(otg_get_transceiver);
  */
 void otg_put_transceiver(struct otg_transceiver *x)
 {
-	put_device(x->dev);
+	if (x)
+		put_device(x->dev);
 }
 EXPORT_SYMBOL(otg_put_transceiver);