ARM: dts: at91: sama5d2: add QSPI nodes

This patch adds DT nodes for sama5d2 QSPI controllers.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
[claudiu.beznea@microchip.com: change subject to match the desired prefix]
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>