Remove meaningsless stats

Showing dcb addresses, the number of fds and the events is
meaningless as the information is completely transient and
is likely to have changed the moment is was displayed.

include/maxscale/poll_core.h

@@ -72,11 +72,7 @@ typedef enum
  */
 typedef struct
 {
-    THREAD_STATE   state;       /*< Current thread state */
-    int            n_fds;       /*< No. of descriptors thread is processing */
-    MXS_POLL_DATA *cur_data;    /*< Current MXS_POLL_DATA being processed */
-    uint32_t       event;       /*< Current event being processed */
-    uint64_t       cycle_start; /*< The time when the poll loop was started */
+    THREAD_STATE state;       /*< Current thread state */
 } THREAD_DATA;
 
 extern THREAD_DATA *thread_data;