Updates kvmx: 515f71c Adds virtio_rng config

diff --git a/kvmx b/kvmx
index 44d63e4998939079c4a1f0fecf352177c16ffcd6..515f71c62b767a543f0ab597be76b08203b91e6b 160000 (submodule)
--- a/kvmx
+++ b/kvmx
@@ -1 +1 @@
-Subproject commit 44d63e4998939079c4a1f0fecf352177c16ffcd6
+Subproject commit 515f71c62b767a543f0ab597be76b08203b91e6b