dt-bindings: watchdog: Realtek Otto WDT binding

Add a binding description for Realtek's watchdog timer as found on
several of their MIPS-based SoCs (codenamed Otto), such as the RTL838x,
RTL839x, and RTL930x series of switch SoCs.

Signed-off-by: Sander Vanheule <sander@svanheule.net>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/d832d5b02976dd2c2674d46778f61e5cfcd9b651.1637252610.git.sander@svanheule.net


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