detect/tls.certs: improve buffer init logic

src/detect-tls-certs.c

@@ -143,8 +143,8 @@ static InspectionBuffer *TlsCertsGetData(DetectEngineThreadCtx *det_ctx,
 
     InspectionBuffer *buffer =
             InspectionBufferMultipleForListGet(det_ctx, list_id, cbdata->local_id);
-    if (buffer == NULL)
+    if (buffer == NULL || buffer->initialized)
-        return NULL;
+        return buffer;
 
     const SSLState *ssl_state = (SSLState *)f->alstate;
     const SSLStateConnp *connp;