Fix a potential leak of nl_msg objects

It was discovered on other repos that a leak can
be caused by repeated usage of create().

Bug: 26116598
Change-Id: Ie6cd318171e58d3ffa1a6c8f58cfa38ea7d78b00
diff --git a/bcmdhd/wifi_hal/cpp_bindings.cpp b/bcmdhd/wifi_hal/cpp_bindings.cpp
index 5b085d8..399199d 100644
--- a/bcmdhd/wifi_hal/cpp_bindings.cpp
+++ b/bcmdhd/wifi_hal/cpp_bindings.cpp
@@ -538,6 +538,9 @@
 }
 
 int WifiRequest::create(int family, uint8_t cmd, int flags, int hdrlen) {
+
+    destroy();
+
     mMsg = nlmsg_alloc();
     if (mMsg != NULL) {
         genlmsg_put(mMsg, /* pid = */ 0, /* seq = */ 0, family,