Update UTCP to correctly handle timeouts sending data.

[meshlink] / src / utcp

diff --git a/src/utcp b/src/utcp
index cb9223d3b895f1edb35bf7a6fd3aa9305de3f1db..6ef1b39de8c0b0537da02b212acaba3242afe142 160000 (submodule)
--- a/src/utcp
+++ b/src/utcp
@@ -1 +1 @@
-Subproject commit cb9223d3b895f1edb35bf7a6fd3aa9305de3f1db
+Subproject commit 6ef1b39de8c0b0537da02b212acaba3242afe142