vmbus: add support for dynamic device id's

This patch adds sysfs interface to dynamically bind new UUID values
to existing VMBus device. This is useful for generic UIO driver to
act similar to uio_pci_generic.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/hyperv.h

@@ -1119,6 +1119,12 @@ struct hv_driver {
 
 	struct device_driver driver;
 
+	/* dynamic device GUID's */
+	struct  {
+		spinlock_t lock;
+		struct list_head list;
+	} dynids;
+
 	int (*probe)(struct hv_device *, const struct hv_vmbus_device_id *);
 	int (*remove)(struct hv_device *);
 	void (*shutdown)(struct hv_device *);