spi: dt-bindings: atmel,at91rm9200-spi: add sam9x7 compatible

Add sam9x7 compatible to DT bindings documentation.
Signed-off-by: Varshini Rajendran <varshini.rajendran@microchip.com>
Link: https://lore.kernel.org/r/Message-Id: <20230623203056.689705-33-varshini.rajendran@microchip.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/atmel,at91rm9200-spi.yaml

@@ -19,6 +19,7 @@ properties:
       - const: atmel,at91rm9200-spi
       - items:
           - const: microchip,sam9x60-spi
+          - const: microchip,sam9x7-spi
           - const: atmel,at91rm9200-spi
 
   reg: