Drivers: hv: Make the vmbus driver unloadable

It turns out that the vmbus driver can be made unloadable. Make it
unloadable.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 0aee112..6d7d286 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -611,6 +611,7 @@
 
 struct vmbus_channel *relid2channel(u32 relid);
 
+void vmbus_free_channels(void);
 
 /* Connection interface */