ARM: dts: at91: sam9x60: add device tree for soc and board

Add device tree files for SAM9X60 SoC and SAM9X60-EK board.

Signed-off-by: Sandeep Sheriker Mallikarjun <sandeepsheriker.mallikarjun@microchip.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/1579085987-13976-6-git-send-email-claudiu.beznea@microchip.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>