soc/intel/xeon_sp: Fix devicetree walking up

Connect the PCI domain to the bus to allow walking the devicetree
up. This is required to figure out which PCI domain a device
belongs to.

Change-Id: I8cc50cabf7ad540c52498e1ffe7f9246550ed87b
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80089
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Shuo Liu <shuo.liu@intel.com>
diff --git a/src/soc/intel/xeon_sp/chip_common.c b/src/soc/intel/xeon_sp/chip_common.c
index c1b331b..0411a03 100644
--- a/src/soc/intel/xeon_sp/chip_common.c
+++ b/src/soc/intel/xeon_sp/chip_common.c
@@ -77,6 +77,7 @@
 	}
 
 	struct bus *bus = dev->link_list;
+	bus->dev = dev;
 	bus->secondary = sr->BusBase;
 	bus->subordinate = sr->BusBase;
 	bus->max_subordinate = sr->BusLimit;