dt-bindings: PCI: Add STM32MP25 PCIe Root Complex bindings

dt-bindings: PCI: Add STM32MP25 PCIe Root Complex bindings

Document the bindings for STM32MP25 PCIe Controller configured in
root complex mode with one root port.

Supports 4 INTx and MSI interrupts from the ARM GICv2m controller.

STM32 PCIe may be in a power domain which is the case for the STM32MP25
based boards.

Supports WAKE# from wake-gpios

Signed-off-by: Christian Bruel <christian.bruel@foss.st.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://patch.msgid.link/20250820075411.1178729-4-christian.bruel@foss.st.com