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>

diff --cc Documentation/ABI/testing/sysfs-ptp
Simple merge

diff --cc drivers/ptp/ptp_private.h
Simple merge

diff --cc drivers/ptp/ptp_sysfs.c
Simple merge