6659 nvlist_free(NULL) is a no-op

@@ -311,11 +311,10 @@
         if (nb_chipset == INTEL_NB_5100)
                 (void) nvlist_add_uint8(nvl, MCINTEL_NVLIST_NMEM,
                     (uint8_t)nb_number_memory_controllers);
         inb_dimmlist(nvl);
 
-        if (inb_mc_nvl)
                 nvlist_free(inb_mc_nvl);
         inb_mc_nvl = nvl;
 }
 
 static void