dt-bindings: PCI: qcom,pcie-sm8450: Add 'global' interrupt

Qcom PCIe RC controllers are capable of generating 'global' SPI interrupt
to the host CPU. This interrupt can be used by the device driver to
identify events such as PCIe link specific events, safety events, etc...

Hence, document it in the binding along with the existing MSI interrupts.
Though adding a new interrupt will break the ABI, it is required to
accurately describe the hardware.

Link: https://lore.kernel.org/linux-pci/20240828-pci-qcom-hotplug-v4-10-263a385fbbcb@linaro.org


Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>