dm: pmic: Convert uclass to livetree

Update the pmic uclass and all pmics to support a live device tree.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/power/pmic/s5m8767.c b/drivers/power/pmic/s5m8767.c
index 25d673b..f8ae5ea 100644
--- a/drivers/power/pmic/s5m8767.c
+++ b/drivers/power/pmic/s5m8767.c
@@ -54,12 +54,11 @@
 
 static int s5m8767_bind(struct udevice *dev)
 {
-	int node;
-	const void *blob = gd->fdt_blob;
 	int children;
+	ofnode node;
 
-	node = fdt_subnode_offset(blob, dev_of_offset(dev), "regulators");
-	if (node <= 0) {
+	node = dev_read_subnode(dev, "regulators");
+	if (!ofnode_valid(node)) {
 		debug("%s: %s regulators subnode not found!", __func__,
 		      dev->name);
 		return -ENXIO;