binman: Allow text directly in the node

At present text entries use an indirect method to specify the text to use,
with a label pointing to the text itself.

Allow the text to be directly written into the node. This is more
convenient in cases where the text is constant.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/README.entries b/tools/binman/README.entries
index 702fc9f..9cbdbba 100644
--- a/tools/binman/README.entries
+++ b/tools/binman/README.entries
@@ -312,6 +312,8 @@
         that contains the string to place in the entry
     <xxx> (actual name is the value of text-label): contains the string to
         place in the entry.
+    <text>: The text to place in the entry (overrides the above mechanism).
+        This is useful when the text is constant.
 
 Example node:
 
@@ -334,6 +336,13 @@
         message = "a message directly in the node"
     };
 
+or just:
+
+    text {
+        size = <8>;
+        text = "some text directly in the node"
+    };
+
 The text is not itself nul-terminated. This can be achieved, if required,
 by setting the size of the entry to something larger than the text.