dm: core: Update ofnode to read binman-style flash entry

At present ofnode_read_fmap_entry() reads a flash map entry in a format
which is not supported by binman. To allow use to use binman-format
descriptions, update this function.

Also add a simple test.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/dm/of_extra.h b/include/dm/of_extra.h
index 97988b6..ca15df2 100644
--- a/include/dm/of_extra.h
+++ b/include/dm/of_extra.h
@@ -11,7 +11,7 @@
 
 enum fmap_compress_t {
 	FMAP_COMPRESS_NONE,
-	FMAP_COMPRESS_LZO,
+	FMAP_COMPRESS_LZ4,
 };
 
 enum fmap_hash_t {
@@ -26,6 +26,7 @@
 	uint32_t length;
 	uint32_t used;			/* Number of bytes used in region */
 	enum fmap_compress_t compress_algo;	/* Compression type */
+	uint32_t unc_length;			/* Uncompressed length */
 	enum fmap_hash_t hash_algo;		/* Hash algorithm */
 	const uint8_t *hash;			/* Hash value */
 	int hash_size;				/* Hash size */