PCI: cadence: Replace private message routing enums with PCI core definitions

PCI: cadence: Replace private message routing enums with PCI core definitions

The Cadence driver previously defined its own message routing enums (e.g.,
MSG_ROUTING_LOCAL) and message codes, which duplicated existing PCI core
macros (PCIE_MSG_TYPE_R_LOCAL, PCIE_MSG_CODE_ASSERT_INTA, etc.) in
drivers/pci/pci.h. These core definitions align with the PCIe r6.0 spec.

Remove the driver-specific enums and switch to the centralized PCI core
macros. This eliminates redundancy, ensures consistency, and simplifies
future updates. No functional changes are introduced.

Signed-off-by: Hans Zhang <18255117159@163.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Link: https://patch.msgid.link/20250607154913.805027-2-18255117159@163.com