PCI/DOE: Support discovery version 2

PCI/DOE: Support discovery version 2

PCIe r6.1, sec 6.30.1.1 defines a "DOE Discovery Version" field in
the DOE Discovery Request Data Object Contents (3rd DW) as:

15:8 DOE Discovery Version – must be 02h if the Capability Version in
the Data Object Exchange Extended Capability is 02h or greater.

Add support for the version on devices with the DOE v2 capability.

Link: https://lore.kernel.org/r/20240307022006.3657433-1-aik@amd.com
Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>