dt-bindings: i2c: at91: Add sam9x7 compatible string

Add compatible string for sam9x7.
Signed-off-by: Varshini Rajendran <varshini.rajendran@microchip.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>

Documentation/devicetree/bindings/i2c/atmel,at91sam-i2c.yaml

@@ -25,7 +25,9 @@ properties:
               - atmel,sama5d2-i2c
               - microchip,sam9x60-i2c
       - items:
-          - const: microchip,sama7g5-i2c
+          - enum:
+              - microchip,sama7g5-i2c
+              - microchip,sam9x7-i2c
           - const: microchip,sam9x60-i2c
 
   reg: