device/device.h: Drop multiple links

Multiple links are unused throughout the tree and make the code more
confusing as an iteration over all busses is needed to get downstream
devices. This also not done consistently e.g. the allocator does not
care about multiple links on busses. A better way of dealing multiple
links below a device is to feature dummy devices with each their
respective bus.

This drops the sconfig capability to declare the same device multiple
times which was previously used to declare multiple links.

Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Change-Id: Iab6fe269faef46ae77ed1ea425440cf5c7dbd49b
Reviewed-on: https://review.coreboot.org/c/coreboot/+/78328
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jincheng Li <jincheng.li@intel.com>
Reviewed-by: Lean Sheng Tan <sheng.tan@9elements.com>
diff --git a/src/northbridge/amd/pi/00730F01/northbridge.c b/src/northbridge/amd/pi/00730F01/northbridge.c
index a4409fb..5e82ccd 100644
--- a/src/northbridge/amd/pi/00730F01/northbridge.c
+++ b/src/northbridge/amd/pi/00730F01/northbridge.c
@@ -235,7 +235,6 @@
 				    unsigned long *current, uint16_t *ivhd_length)
 {
 	struct device *sibling;
-	struct bus *link;
 
 	if (!root_level) {
 		root_level = malloc(sizeof(int8_t));
@@ -254,11 +253,11 @@
 		}
 	}
 
-	for (link = dev->link_list; link; link = link->next)
-		for (sibling = link->children; sibling; sibling =
-		     sibling->sibling)
+	if (dev->link_list) {
+		for (sibling = dev->link_list->children; sibling; sibling = sibling->sibling)
 			add_ivhd_device_entries(dev, sibling, depth + 1, depth, root_level,
 						current, ivhd_length);
+	}
 
 	free(root_level);
 }