PCI: hv: Document missing hv_pci_protocol_negotiation() parameter

Add missing documentation for the parameter "version" and "num_version"
of the hv_pci_protocol_negotiation() function and resolve build time
kernel-doc warnings:

  drivers/pci/controller/pci-hyperv.c:2535: warning: Function parameter
  or member 'version' not described in 'hv_pci_protocol_negotiation'

  drivers/pci/controller/pci-hyperv.c:2535: warning: Function parameter
  or member 'num_version' not described in 'hv_pci_protocol_negotiation'

No change to functionality intended.

Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
Link: https://lore.kernel.org/r/20200925234753.1767227-1-kw@linux.com
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>