Change qemu config to allow it to write into seral0.

diff --git a/jailhouse b/jailhouse
index 287503fb40db8184c5f1a438543e72e8bbdef436..7319ef5061d4d6288fb982147e07286a8a827a93 160000 (submodule)
--- a/jailhouse
+++ b/jailhouse
@@ -1 +1 @@
-Subproject commit 287503fb40db8184c5f1a438543e72e8bbdef436
+Subproject commit 7319ef5061d4d6288fb982147e07286a8a827a93