pci: pci-uclass: Make DT subnode parse optional

Parse subnode DT properties only if parent node is valid.
Otherwise, assert is triggered on ofnode_valid in ofnode_first_subnode
from dev_for_each_subnode.

Signed-off-by: Suneel Garapati <sgarapati@marvell.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Cc: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c
index fde5b83..cf1bbcc 100644
--- a/drivers/pci/pci-uclass.c
+++ b/drivers/pci/pci-uclass.c
@@ -696,7 +696,8 @@
 	      find_id->vendor, find_id->device);
 
 	/* Determine optional OF node */
-	pci_dev_find_ofnode(parent, bdf, &node);
+	if (ofnode_valid(dev_ofnode(parent)))
+		pci_dev_find_ofnode(parent, bdf, &node);
 
 	if (ofnode_valid(node) && !ofnode_is_available(node)) {
 		debug("%s: Ignoring disabled device\n", __func__);