Au1xx0: really set KSEG0 to uncached on reboot

Hello.

Just found really old buglet in AMD Au1xx0 restart code: instead of
modifying the whole CP0 Config.K0 field to 010b (meaning KSEG0 uncached) before flushing the caches and resetting a board, it only sets bit 1 of that reg. which is effectively a NOP since Config.K0 == 011b as the kernel sets it up (which is also its default value for Au1xx0).

WBR, Sergei

index 65b84db..4ffcced 100644
@@ -151,7 +151,7 @@ void au1000_restart(char *command)
 	}
 
 	set_c0_status(ST0_BEV | ST0_ERL);
-	set_c0_config(CONF_CM_UNCACHED);
+	change_c0_config(CONF_CM_CMASK, CONF_CM_UNCACHED);
 	flush_cache_all();
 	write_c0_wired(0);