dt-bindings: watchdog: indentation, quotes and white-space cleanup

Minor cleanup without functional impact:
1. Indent DTS examples to preferred four-spaces (more readable for DTS),
2. Drop unneeded quotes,
3. Add/drop blank lines to make the code readable.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Acked-by: Justin Chen <justinpopo6@gmail.com>
Acked-by: Neil Armstrong <neil.armstrong@linaro.org>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230415095112.51257-2-krzysztof.kozlowski@linaro.org


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