update vkh

diff --git a/vkh b/vkh
index 7878c4fef0d0afb1b07b37b62306f59e037cf32a..90c2fca528bb89b4dfeea37b6aa018e0486c5d98 160000 (submodule)
--- a/vkh
+++ b/vkh
@@ -1 +1 @@
-Subproject commit 7878c4fef0d0afb1b07b37b62306f59e037cf32a
+Subproject commit 90c2fca528bb89b4dfeea37b6aa018e0486c5d98