Staging: hv: make *context a real pointer in struct hv_device

This is really the struct vmbus_channel for the device, not a void
pointer, so use the real structure to ensure type safety everywhere.

Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/hv/vmbus_api.h

@@ -152,7 +152,7 @@ struct hv_device {
 	/* the device instance id of this device */
 	struct hv_guid deviceInstance;
 
-	void *context;
+	struct vmbus_channel *context;
 
 	/* Device extension; */
 	void *Extension;