Replace RW lock with mutex, shared_mutex

Test: built, flashed, booted
      system/netd/tests/runtests.sh passes
Change-Id: I42b52d815b6ba0ba6f93dc27e83a900d2abec715
diff --git a/server/BandwidthController.h b/server/BandwidthController.h
index 4b72f18..882dea4 100644
--- a/server/BandwidthController.h
+++ b/server/BandwidthController.h
@@ -21,14 +21,13 @@
 #include <string>
 #include <utility>
 #include <vector>
-
-#include <utils/RWLock.h>
+#include <mutex>
 
 #include "NetdConstants.h"
 
 class BandwidthController {
 public:
-    android::RWLock lock;
+    std::mutex lock;
 
     BandwidthController();