gogole-usb: add option to not bridge the usb link

Google-Bug-Id: 543188543
Tested: verified on mimik that the link is not bridged.
Change-Id: I5148f4aee99410c020545db60052e3e7cae2e08f
Signed-off-by: Yuxiao Zhang <yuxiaozhang@google.com>

meta-gbmc-staging

diff --git a/meta-gbmc-staging b/meta-gbmc-staging
index 3b840c0..649e144 160000
--- a/meta-gbmc-staging
+++ b/meta-gbmc-staging
@@ -1 +1 @@
-Subproject commit 3b840c03cbd8329fa699aecda2c2e8b3126c1cc3
+Subproject commit 649e144242b127a1fca3298cbceaa60dc04fc40a