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>

src/soc/intel/xeon_sp/chip_common.c

@@ -77,6 +77,7 @@ void iio_pci_domain_scan_bus(struct device *dev)
 	}
 
 	struct bus *bus = dev->link_list;
+	bus->dev = dev;
 	bus->secondary = sr->BusBase;
 	bus->subordinate = sr->BusBase;
 	bus->max_subordinate = sr->BusLimit;

src/soc/intel/xeon_sp/spr/ioat.c

@@ -45,6 +45,7 @@ static void create_ioat_domain(struct bus *const upstream, const unsigned int do
 		die("%s: out of memory.\n", __func__);
 
 	struct bus *const bus = domain->link_list;
+	bus->dev = domain;
 	bus->secondary = bus_base;
 	bus->subordinate = bus->secondary;
 	bus->max_subordinate = bus_limit;