dt-bindings: interrupt-controller: Add support for sam9x7 aic

Document the support added for the Advanced interrupt controller(AIC)
chip in the sam9x7 SoC family. New compatible is introduced to capture
the differences like the number of interrupts supported in the
integration of the IP to that of the previous designs.

Signed-off-by: Varshini Rajendran <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Acked-by: Rob Herring (Arm) <[e-mail]>
Acked-by: Dharma Balasubiramani <[e-mail]>
Link: https://lore.kernel.org/all/[e-mail]

Documentation/devicetree/bindings/interrupt-controller/atmel,aic.yaml

···
       - atmel,sama5d3-aic
       - atmel,sama5d4-aic
       - microchip,sam9x60-aic
+      - microchip,sam9x7-aic
 
   reg:
     maxItems: 1