device/device.h: Rename busses for clarity

This renames bus to upstream and link_list to downstream.

Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Change-Id: I80a81b6b8606e450ff180add9439481ec28c2420
Reviewed-on: https://review.coreboot.org/c/coreboot/+/78330
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
diff --git a/src/northbridge/intel/sandybridge/pcie.c b/src/northbridge/intel/sandybridge/pcie.c
index 96fb12f..244b0f5 100644
--- a/src/northbridge/intel/sandybridge/pcie.c
+++ b/src/northbridge/intel/sandybridge/pcie.c
@@ -13,8 +13,8 @@
 	if (dev->path.type != DEVICE_PATH_PCI)
 		return NULL;
 
-	assert(dev->bus);
-	if (dev->bus->secondary == 0)
+	assert(dev->upstream);
+	if (dev->upstream->secondary == 0)
 		switch (dev->path.pci.devfn) {
 		case PCI_DEVFN(1, 0):
 			return "PEGP";
@@ -26,12 +26,12 @@
 			return "PEG6";
 		};
 
-	struct device *const port = dev->bus->dev;
+	struct device *const port = dev->upstream->dev;
 	assert(port);
-	assert(port->bus);
+	assert(port->upstream);
 
 	if (dev->path.pci.devfn == PCI_DEVFN(0, 0) &&
-	    port->bus->secondary == 0 &&
+	    port->upstream->secondary == 0 &&
 	    (port->path.pci.devfn == PCI_DEVFN(1, 0) ||
 	     port->path.pci.devfn == PCI_DEVFN(1, 1) ||
 	     port->path.pci.devfn == PCI_DEVFN(1, 2) ||