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/drivers/nxp/uwb/uwb.c b/src/drivers/nxp/uwb/uwb.c
index 0f5ba47..b828657 100644
--- a/src/drivers/nxp/uwb/uwb.c
+++ b/src/drivers/nxp/uwb/uwb.c
@@ -15,10 +15,10 @@
 	struct device *spi_dev;
 	struct device_operations *ops;
 
-	if (!dev->bus || !dev->bus->dev)
+	if (!dev->upstream || !dev->upstream->dev)
 		return -1;
 
-	spi_dev = dev->bus->dev;
+	spi_dev = dev->upstream->dev;
 	ops = spi_dev->ops;
 
 	if (ops && ops->ops_spi_bus && ops->ops_spi_bus->dev_to_bus)