dt-bindings: PCI: Add binding for Toshiba TC9563 PCIe switch

dt-bindings: PCI: Add binding for Toshiba TC9563 PCIe switch

Add a device tree binding for the Toshiba TC9563 PCIe switch, which
provides an Ethernet MAC integrated to the 3rd downstream port and
two downstream PCIe ports.

Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Acked-by: Manivannan Sadhasivam <mani@kernel.org>
Link: https://patch.msgid.link/20251101-tc9563-v9-1-de3429f7787a@oss.qualcomm.com