ARM: dts: at91: sam9x7: add device tree for SoC

Add device tree file for SAM9X7 SoC family.

Co-developed-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Varshini Rajendran <varshini.rajendran@microchip.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>
Link: https://lore.kernel.org/r/20241010120432.93151-1-varshini.rajendran@microchip.com
Signed-off-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>

Author: varshini-rajendran