selinux: avoid printk_ratelimit()

The usage of printk_ratelimit() is discouraged, see
include/linux/printk.h, thus use pr_warn_ratelimited().

While editing this line address the following checkpatch warning:

    WARNING: Integer promotion: Using 'h' in '%hu' is unnecessary
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

security/selinux/ss/services.c

@@ -633,8 +633,7 @@ static void context_struct_compute_av(struct policydb *policydb,
 	}
 
 	if (unlikely(!tclass || tclass > policydb->p_classes.nprim)) {
-		if (printk_ratelimit())
-			pr_warn("SELinux:  Invalid class %hu\n", tclass);
+		pr_warn_ratelimited("SELinux:  Invalid class %u\n", tclass);
 		return;
 	}