upl: Add support for Universal Payload in SPL

Add the basic code to create a handoff structure in SPL, so it can be
passed to the next phase. For now this is not plumbed in.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/spl.h b/include/spl.h
index 1eebea3..f92089b 100644
--- a/include/spl.h
+++ b/include/spl.h
@@ -1073,4 +1073,20 @@
 {
 	return IS_ENABLED(CONFIG_SPL_GZIP) || IS_ENABLED(CONFIG_SPL_LZMA);
 }
+
+/**
+ * spl_write_upl_handoff() - Write a Universal Payload hand-off structure
+ *
+ * @spl_image: Information about the image being booted
+ * Return: 0 if OK, -ve on error
+ */
+int spl_write_upl_handoff(struct spl_image_info *spl_image);
+
+/**
+ * spl_upl_init() - Get UPL ready for information to be added
+ *
+ * This must be called before upl_add_image(), etc.
+ */
+void spl_upl_init(void);
+
 #endif