[AGPGART] Fix up sgi-agp bug with no devices on bus.

Signed-off-by: NEric Kunze <ekunze@sgi.com>
Signed-off-by: NDave Jones <davej@redhat.com>

drivers/char/agp/sgi-agp.c

@@ -288,6 +288,8 @@ static int __devinit agp_sgi_init(void)
 	j = 0;
 	list_for_each_entry(info, &tioca_list, ca_list) {
 		struct list_head *tmp;
+		if (list_empty(info->ca_devices))
+			continue;
 		list_for_each(tmp, info->ca_devices) {
 			u8 cap_ptr;
 			pdev = pci_dev_b(tmp);