binman: Support updating the device tree with calc'd info

It is useful to write the position and size of each entry back to the
device tree so that U-Boot can access this at runtime. Add a feature to
support this, along with associated tests.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/README b/tools/binman/README
index 8b598a7..207928a 100644
--- a/tools/binman/README
+++ b/tools/binman/README
@@ -669,13 +669,11 @@
 -----
 
 Some ideas:
-- Fill out the device tree to include the final position and size of each
-  entry (since the input file may not always specify these). See also
-  'Access to binman entry positions at run time' above
 - Use of-platdata to make the information available to code that is unable
   to use device tree (such as a very small SPL image)
 - Allow easy building of images by specifying just the board name
-- Produce a full Python binding for libfdt (for upstream)
+- Produce a full Python binding for libfdt (for upstream). This is nearing
+    completion but some work remains
 - Add an option to decode an image into the constituent binaries
 - Support building an image for a board (-b) more completely, with a
   configurable build directory