vringh: add MODULE_DESCRIPTION()

Fix the allmodconfig 'make w=1' issue:

WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/vhost/vringh.o
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Message-Id: <20240516-md-vringh-v1-1-31bf37779a5a@quicinc.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

drivers/vhost/vringh.c

@@ -1614,4 +1614,5 @@ EXPORT_SYMBOL(vringh_need_notify_iotlb);
 
 #endif
 
+MODULE_DESCRIPTION("host side of a virtio ring");
 MODULE_LICENSE("GPL");