conman: Time out connection checks after 5s.

Bug: 34040473
Change-Id: I8d93c110a6b18259ac0a0eccbc5d0cc8eb635eb7
diff --git a/conman/interface.py b/conman/interface.py
index 245ca27..fbef47e 100755
--- a/conman/interface.py
+++ b/conman/interface.py
@@ -82,7 +82,7 @@
     if 'default' not in self.current_routes():
       return False
 
-    cmd = [self.CONNECTION_CHECK, '-I', self.name]
+    cmd = ['timeout', '5', self.CONNECTION_CHECK, '-I', self.name]
     if check_acs:
       cmd.append('-a')