Updates kvmx: 378f8c3 Fix: kvmx up: fail if basebox is not available

diff --git a/kvmx b/kvmx
index 3f145976890e18b67019de57426a70d50887f0f2..378f8c37ce5eedb69a0aa4932f722c6c1eccbdbf 160000 (submodule)
--- a/kvmx
+++ b/kvmx
@@ -1 +1 @@
-Subproject commit 3f145976890e18b67019de57426a70d50887f0f2
+Subproject commit 378f8c37ce5eedb69a0aa4932f722c6c1eccbdbf