dm: device: Add newline to debug() messages

Some of these are missing a newline. Add it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/core/device.c b/drivers/core/device.c
index 6793e1c..963b16f 100644
--- a/drivers/core/device.c
+++ b/drivers/core/device.c
@@ -234,7 +234,7 @@
 void *dev_get_platdata(struct udevice *dev)
 {
 	if (!dev) {
-		dm_warn("%s: null device", __func__);
+		dm_warn("%s: null device\n", __func__);
 		return NULL;
 	}
 
@@ -244,7 +244,7 @@
 void *dev_get_priv(struct udevice *dev)
 {
 	if (!dev) {
-		dm_warn("%s: null device", __func__);
+		dm_warn("%s: null device\n", __func__);
 		return NULL;
 	}
 
@@ -254,7 +254,7 @@
 void *dev_get_parentdata(struct udevice *dev)
 {
 	if (!dev) {
-		dm_warn("%s: null device", __func__);
+		dm_warn("%s: null device\n", __func__);
 		return NULL;
 	}