fix panic in powernow_k8_verify on MP but PSB systems

Instead of -ENODEV; powernow_k8_cpu_init returns 0 if it's running on a MP system but PSB BIOS is tried... this causes a panic in powernow_k8_verify, as can be seen at
http://forums.gentoo.org/viewtopic.php?t=177423

@@ -945,7 +945,7 @@
 		if ((num_online_cpus() != 1) || (num_possible_cpus() != 1)) {
 			printk(KERN_INFO PFX "MP systems not supported by PSB BIOS structure\n");
 			kfree(data);
-			return 0;
+			return -ENODEV;
 		}
 		rc = find_psb_table(data);
 		if (rc) {

Seems to make sense.
Applied.

Thanks for this too. I'll start propagating these through the cpufreq changes.

Dave