dt-bindings: watchdog: Drop unneeded quotes

Cleanup bindings dropping unneeded quotes. Once all these are fixed,
checking for this can be enabled in yamllint.

Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: Hector Martin <marcan@marcan.st>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Florian Fainelli <f.fainelli@gmail.com> #brcm,bcm7038-wdt.yaml
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230317233643.3969019-1-robh@kernel.org


Signed-off-by: Rob Herring <robh@kernel.org>