board: atmel: add sama5d2_ptc_ek board

Add the SAMA5D2 PTC EK board and remove the SAMA5D2 PTC ENGI board
which was a prototype.

Signed-off-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Wenyou Yang <wenyou.yang@microchip.com>