dt-bindings: serial: atmel,at91-usart: add microchip,lan9691-usart

Document Microchip LAN969x USART compatible.

Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>
Link: https://patch.msgid.link/20260302112153.464422-2-robert.marko@sartura.hr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: robimarko

Documentation/devicetree/bindings/serial/atmel,at91-usart.yaml

@@ -24,6 +24,7 @@ properties:
           - const: atmel,at91sam9260-usart
       - items:
           - enum:
+              - microchip,lan9691-usart
               - microchip,sam9x60-usart
               - microchip,sam9x7-usart
               - microchip,sama7d65-usart