powerpc: Use str_plural() in cpu_init_thread_core_maps()

Fixes the following Coccinelle/coccicheck warning reported by
string_choices.cocci:

	opportunity for str_plural(tpc)
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240331222249.107467-2-thorsten.blum@toblux.com

arch/powerpc/kernel/setup-common.c

@@ -405,7 +405,7 @@ static void __init cpu_init_thread_core_maps(int tpc)
 		cpumask_set_cpu(i, &threads_core_mask);
 
 	printk(KERN_INFO "CPU maps initialized for %d thread%s per core\n",
-	       tpc, tpc > 1 ? "s" : "");
+	       tpc, str_plural(tpc));
 	printk(KERN_DEBUG " (thread shift is %d)\n", threads_shift);
 }