dt-bindings: watchdog: sama5d4-wdt: convert to yaml

Convert the old txt binding to yaml format.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210527100120.266796-1-eugen.hristev@microchip.com


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