hv: hv_util: move vmbus_open() to a later place

Before the line vmbus_open() returns, srv->util_cb can be already running
and the variables, like util_fw_version, are needed by the srv->util_cb.

So we have to make sure the variables are initialized before the vmbus_open().

CC: "K. Y. Srinivasan" <kys@microsoft.com>
Reviewed-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NDexuan Cui <decui@microsoft.com>
Signed-off-by: NK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/hv_util.c

@@ -340,12 +340,8 @@ static int util_probe(struct hv_device *dev,
 
 	set_channel_read_state(dev->channel, false);
 
-	ret = vmbus_open(dev->channel, 4 * PAGE_SIZE, 4 * PAGE_SIZE, NULL, 0,
-			srv->util_cb, dev->channel);
-	if (ret)
-		goto error;
-
 	hv_set_drvdata(dev, srv);
+
 	/*
 	 * Based on the host; initialize the framework and
 	 * service version numbers we will negotiate.
@@ -365,6 +361,11 @@ static int util_probe(struct hv_device *dev,
 		hb_srv_version = HB_VERSION;
 	}
 
+	ret = vmbus_open(dev->channel, 4 * PAGE_SIZE, 4 * PAGE_SIZE, NULL, 0,
+			srv->util_cb, dev->channel);
+	if (ret)
+		goto error;
+
 	return 0;
 
 error: