dt-bindings: watchdog: sama5d4-wdt: add compatible for sam9x7-wdt

Add compatible microchip,sam9x7-wdt to DT bindings documentation.

Signed-off-by: Varshini Rajendran <varshini.rajendran@microchip.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20240223172627.672316-1-varshini.rajendran@microchip.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>