Support 4 PTP programmable pins with only PTP_PF_PEROUT function
for now. The PTP_PF_EXTTS function will be supported in the
future, and it should be implemented separately for Felix and
Ocelot, because of different hardware interrupt implementation
in them.

Since the hardware is not able to support absolute start time,
the periodic clock request only allows start time 0 0. But nsec
could be accepted for PPS case for phase adjustment.
Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>