net: lan743x: Add support for PTP-IO Event Input External Timestamp (extts)

PTP-IOs block provides for time stamping PTP-IO input events.
PTP-IOs are numbered from 0 to 11.
When a PTP-IO is enabled by the corresponding bit in the PTP-IO
Capture Configuration Register, a rising or falling edge,
respectively, will capture the 1588 Local Time Counter

Signed-off-by: Raju Lakkaraju <Raju.Lakkaraju@microchip.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>