PCI: Move CXL DVSEC definitions into uapi/linux/pci_regs.h

PCI: Move CXL DVSEC definitions into uapi/linux/pci_regs.h

The CXL DVSECs are currently defined in cxl/core/cxlpci.h. These are not
accessible to other subsystems. Move these to uapi/linux/pci_regs.h.

The CXL DVSEC definitions will be renamed and reformatted to fit better
with existing defines.

Signed-off-by: Terry Bowman <terry.bowman@amd.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20260114182055.46029-2-terry.bowman@amd.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>