dm: core: Export a new function to read platdata

Add a new internal function, device_ofdata_to_platdata() to handle
allocating private space associated with each device and reading the
platform data from the device tree.

Call this new function from device_probe().

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/core/device.c b/drivers/core/device.c
index f0c2305..9506c7d 100644
--- a/drivers/core/device.c
+++ b/drivers/core/device.c
@@ -311,12 +311,11 @@
 	return priv;
 }
 
-int device_probe(struct udevice *dev)
+int device_ofdata_to_platdata(struct udevice *dev)
 {
 	const struct driver *drv;
 	int size = 0;
 	int ret;
-	int seq;
 
 	if (!dev)
 		return -EINVAL;
@@ -369,6 +368,32 @@
 			goto fail;
 	}
 
+	return 0;
+fail:
+	device_free(dev);
+
+	return ret;
+}
+
+int device_probe(struct udevice *dev)
+{
+	const struct driver *drv;
+	int ret;
+	int seq;
+
+	if (!dev)
+		return -EINVAL;
+
+	if (dev->flags & DM_FLAG_ACTIVATED)
+		return 0;
+
+	drv = dev->driver;
+	assert(drv);
+
+	ret = device_ofdata_to_platdata(dev);
+	if (ret)
+		goto fail;
+
 	/* Ensure all parents are probed */
 	if (dev->parent) {
 		ret = device_probe(dev->parent);