dt-bindings: reset: atmel,at91sam9260-reset: add sam9x7

Add documentation for SAM9X7 reset controller.

Signed-off-by: Varshini Rajendran <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Acked-by: Philipp Zabel <[e-mail]>
Acked-by: Dharma Balasubiramani <[e-mail]>
Reviewed-by: Tudor Ambarus <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Philipp Zabel <[e-mail]>

Documentation/devicetree/bindings/reset/atmel,at91sam9260-reset.yaml

···
       - items:
           - const: atmel,sama5d3-rstc
           - const: atmel,at91sam9g45-rstc
+      - items:
+          - enum:
+              - microchip,sam9x7-rstc
+          - const: microchip,sam9x60-rstc
 
   reg:
     minItems: 1