net: dsa: microchip: ptp: lan937x: Enable periodic output in LED pins

There is difference in implementation of per_out pins between KSZ9563
and LAN937x. In KSZ9563, Timestamping control register (0x052C) bit 6,
if 1 - timestamp input and 0 - trigger output. But it is opposite for
LAN937x 1 - trigger output and 0 - timestamp input.
As per per_out gpio pins, KSZ9563 has four Led pins and two dedicated
gpio pins. But in LAN937x dedicated gpio pins are removed instead there
are up to 10 LED pins out of which LED_0 and LED_1 can be mapped to PTP
tou 0, 1 or 2. This patch sets the bit 6 in 0x052C register and
configure the LED override and source register for LAN937x series of
switches alone.

Signed-off-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>