ptp: expose the programmable pins via sysfs

This patch adds the sysfs hooks needed in order to get and set the
programmable pin settings.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/ptp/ptp_private.h

@@ -51,6 +51,9 @@ struct ptp_clock {
 	struct mutex pincfg_mux; /* protect concurrent info->pin_config access */
 	wait_queue_head_t tsev_wq;
 	int defunct; /* tells readers to go away when clock is being removed */
+	struct device_attribute *pin_dev_attr;
+	struct attribute **pin_attr;
+	struct attribute_group pin_attr_group;
 };
 
 /*