PCI: hv: Use vPCI protocol version 1.2

Update the Hyper-V vPCI driver to use the Server-2016 version of the vPCI
protocol, fixing MSI creation and retargeting issues.

Signed-off-by: Jork Loeser <jloeser@microsoft.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>