Update bmusb.

diff --git a/bmusb b/bmusb
index 3947e570dc2ab15f4993d0fa4cfd44d8070f0107..b7e6e2e7df1bbae97a1b62112d9c8c67df212f44 160000 (submodule)
--- a/bmusb
+++ b/bmusb
@@ -1 +1 @@
-Subproject commit 3947e570dc2ab15f4993d0fa4cfd44d8070f0107
+Subproject commit b7e6e2e7df1bbae97a1b62112d9c8c67df212f44