dt-bindings: PCI: Add ASPEED PCIe RC support

dt-bindings: PCI: Add ASPEED PCIe RC support

ASPEED AST2600 provides one PCIe RC with 5GT/s and AST2700 provides three
PCIe RC for two 16GT/s and one 5GT/s. All of these RCs have just one Root
Port to connect to PCIe device. And also have Mem, I/O access, legacy
interrupt and MSI.

Signed-off-by: Jacky Chou <jacky_chou@aspeedtech.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20251216-upstream_pcie_rc-v7-2-4aeb0f53c4ce@aspeedtech.com