dt-bindings: pinctrl: apple,pinctrl: Add apple,t8112-pinctrl compatible

This new SoC uses the same pinctrl hardware, so just add a new per-SoC
compatible.

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