expo: Correct some swallowed errors in scene

Return the reported error, rather than assuming it is -ENOMEM

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/boot/scene.c b/boot/scene.c
index 08ed85e..9c4466c 100644
--- a/boot/scene.c
+++ b/boot/scene.c
@@ -137,7 +137,7 @@
 			    sizeof(struct scene_obj_img),
 			    (struct scene_obj **)&img);
 	if (ret < 0)
-		return log_msg_ret("obj", -ENOMEM);
+		return log_msg_ret("obj", ret);
 
 	img->data = data;
 
@@ -157,7 +157,7 @@
 			    sizeof(struct scene_obj_txt),
 			    (struct scene_obj **)&txt);
 	if (ret < 0)
-		return log_msg_ret("obj", -ENOMEM);
+		return log_msg_ret("obj", ret);
 
 	txt->str_id = str_id;
 
@@ -183,7 +183,7 @@
 			    sizeof(struct scene_obj_txt),
 			    (struct scene_obj **)&txt);
 	if (ret < 0)
-		return log_msg_ret("obj", -ENOMEM);
+		return log_msg_ret("obj", ret);
 
 	txt->str_id = str_id;