ARM: dts: lan966x: Add support for SMA connectors

The pcb8309 has 2 SMA connectors which are connected to the lan966x
chip. The lan966x can generate 1PPS output on one of them and it can
receive 1PPS input on the other one.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20230421113758.3465678-1-horatiu.vultur@microchip.com