dt-bindings: pwm: at91: Add sam9x7 compatible strings list

Add compatible strings list for SAM9X7.
Signed-off-by: Varshini Rajendran <varshini.rajendran@microchip.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20240223172619.672262-1-varshini.rajendran@microchip.comSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

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

@@ -25,6 +25,9 @@ properties:
       - items:
           - const: microchip,sama7g5-pwm
           - const: atmel,sama5d2-pwm
+      - items:
+          - const: microchip,sam9x7-pwm
+          - const: microchip,sam9x60-pwm
 
   reg:
     maxItems: 1