Drivers: hv: Support handling multiple VMBUS versions

The current code hard coded the vmbus version independent of the host
it was running on. Add code to dynamically negotiate the most appropriate
version.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>