dt-bindings: watchdog: apple,wdt: Add t8112-wdt compatible

The block on the Apple M2 SoC is compatible with the existing driver so
add its per-SoC compatible.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Janne Grunau <j@jannau.net>
Signed-off-by: Hector Martin <marcan@marcan.st>