DNP: use the proper free function

g618661b22e introduced a free for a so called memory leak (which wasn't
a real leak due to the pinfo->pool garbage collector) but used the wrong
free function. Let's keep the explicit free but use the right function.

Closes #17462


(cherry picked from commit 029a7fcec5)

epan/dissectors/packet-dnp.c

@@ -3455,7 +3455,7 @@ dissect_dnp3_message(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void*
     else
     {
       /* CRC error - throw away the data. */
-      g_free(al_buffer);
+      wmem_free(pinfo->pool, al_buffer);
       next_tvb = NULL;
     }
   }