6659 nvlist_free(NULL) is a no-op

@@ -2523,11 +2523,10 @@
                 mutex_exit(&stmf_state.stmf_lock);
                 return (ret);
         }
 
         /* Free any existing lists and add this one to the ppd */
-        if (ppd->ppd_nv)
                 nvlist_free(ppd->ppd_nv);
         ppd->ppd_nv = nv;
 
         /* set the token for writes */
         ppd->ppd_token++;

@@ -2596,11 +2595,10 @@
 
         if (*pppd == NULL)
                 return;
 
         *pppd = ppd->ppd_next;
-        if (ppd->ppd_nv)
                 nvlist_free(ppd->ppd_nv);
 
         kmem_free(ppd, ppd->ppd_alloc_size);
 }