Drivers: hv: utils: Rename version definitions to reflect protocol version.

Different Windows host versions may reuse the same protocol version when
negotiating the TimeSync, Shutdown, and Heartbeat protocols. We should only
refer to the protocol version to avoid conflating the two concepts.

Signed-off-by: Alex Ng <alexng@messages.microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>