device/pciexp: add pcie_find_dsn()

Add pcie_find_dsn() to detect and match PCIe device serial
number. In addition, vendor ID is matched when provided.

Change-Id: I54b6dc42c8da47cd7b4447ab23a6a21562c7618
Signed-off-by: Jonathan Zhang <jonzhang@meta.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/54510
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Marc Jones <marc@marcjonesconsulting.com>

src/include/device/pciexp.h

@@ -44,6 +44,9 @@ static inline bool pciexp_is_downstream_port(int type)
 	       type == PCI_EXP_TYPE_PCIE_BRIDGE;
 }
 
+struct device *pcie_find_dsn(const uint64_t serial, const uint16_t vid,
+	struct device *from);
+
 bool pciexp_get_ltr_max_latencies(struct device *dev, u16 *max_snoop, u16 *max_nosnoop);
 
 #endif /* DEVICE_PCIEXP_H */