mm/page_alloc: use str_off_on() helper in build_all_zonelists()

Remove hard-coded strings by using the str_off_on() helper function.

Link: https://lkml.kernel.org/r/20241021091340.5243-2-thorsten.blum@linux.dev
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc.c

@@ -5493,7 +5493,7 @@ void __ref build_all_zonelists(pg_data_t *pgdat)
 
 	pr_info("Built %u zonelists, mobility grouping %s.  Total pages: %ld\n",
 		nr_online_nodes,
-		page_group_by_mobility_disabled ? "off" : "on",
+		str_off_on(page_group_by_mobility_disabled),
 		vm_total_pages);
 #ifdef CONFIG_NUMA
 	pr_info("Policy zone: %s\n", zone_names[policy_zone]);