dm: core: Add a new flag to track platform data

We want to avoid allocating platform data twice. This could happen if
device_probe() is called after device_ofdata_to_platdata() for the same
device.

Add a flag to track whether device_ofdata_to_platdata() has been called on
a device. Check the flag to make sure it doesn't happen twice, and clear
the flag when the data is freed.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/core/device.c b/drivers/core/device.c
index 9506c7d..9f39218 100644
--- a/drivers/core/device.c
+++ b/drivers/core/device.c
@@ -320,7 +320,7 @@
 	if (!dev)
 		return -EINVAL;
 
-	if (dev->flags & DM_FLAG_ACTIVATED)
+	if (dev->flags & DM_FLAG_PLATDATA_VALID)
 		return 0;
 
 	drv = dev->driver;
@@ -368,6 +368,8 @@
 			goto fail;
 	}
 
+	dev->flags |= DM_FLAG_PLATDATA_VALID;
+
 	return 0;
 fail:
 	device_free(dev);