Extend the example program for PTP ancillary functionality with the
ability to configure not only the periodic output's period (frequency),
but also the phase and duty cycle (pulse width) which were newly
introduced.

The ioctl level also needs to be updated to the new PTP_PEROUT_REQUEST2,
since the original PTP_PEROUT_REQUEST doesn't support this
functionality. For an in-tree testing program, not having explicit
backwards compatibility is fine, as it should always be tested with the
current kernel headers and sources.

Tested with an oscilloscope on the felix switch PHC:

echo '2 0' > /sys/class/ptp/ptp1/pins/switch_1588_dat0
./testptp -d /dev/ptp1 -p 1000000000 -w 100000000 -H 1000 -i 0
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>