binman: Refactor binman_entry_find() to allow other nodes

At present we can only read from a top-level binman node entry. Refactor
this function to produce a second local function which supports reading
from any node.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/lib/binman.c b/lib/binman.c
index dc3a880..9098a1d 100644
--- a/lib/binman.c
+++ b/lib/binman.c
@@ -29,25 +29,32 @@
 
 static struct binman_info *binman;
 
-int binman_entry_find(const char *name, struct binman_entry *entry)
+static int binman_entry_find_internal(ofnode node, const char *name,
+				      struct binman_entry *entry)
 {
-	ofnode node;
 	int ret;
 
-	node = ofnode_find_subnode(binman->image, name);
 	if (!ofnode_valid(node))
-		return log_msg_ret("no binman node", -ENOENT);
+		node = binman->image;
+	node = ofnode_find_subnode(node, name);
+	if (!ofnode_valid(node))
+		return log_msg_ret("node", -ENOENT);
 
 	ret = ofnode_read_u32(node, "image-pos", &entry->image_pos);
 	if (ret)
-		return log_msg_ret("bad binman node1", ret);
+		return log_msg_ret("import-pos", ret);
 	ret = ofnode_read_u32(node, "size", &entry->size);
 	if (ret)
-		return log_msg_ret("bad binman node2", ret);
+		return log_msg_ret("size", ret);
 
 	return 0;
 }
 
+int binman_entry_find(const char *name, struct binman_entry *entry)
+{
+	return binman_entry_find_internal(binman->image, name, entry);
+}
+
 void binman_set_rom_offset(int rom_offset)
 {
 	binman->rom_offset = rom_offset;