ppc: simplify one-level sysctl registration for powersave_nap_ctl_table

There is no need to declare an extra tables to just create directory,
this can be easily be done with a prefix path with register_sysctl().

Simplify this registration.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

arch/powerpc/kernel/idle.c

@@ -107,19 +107,11 @@ static struct ctl_table powersave_nap_ctl_table[] = {
 	},
 	{}
 };
-static struct ctl_table powersave_nap_sysctl_root[] = {
-	{
-		.procname	= "kernel",
-		.mode		= 0555,
-		.child		= powersave_nap_ctl_table,
-	},
-	{}
-};
 
 static int __init
 register_powersave_nap_sysctl(void)
 {
-	register_sysctl_table(powersave_nap_sysctl_root);
+	register_sysctl("kernel", powersave_nap_ctl_table);
 
 	return 0;
 }