dt-bindings: pci: apple,pcie: Add t8112 support

The block found in the Apple M2 SoC is compatible with the existing
driver, and supports 4 downstream ports like the t6000 one.

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