libfdt: Bring in proposed pylibfdt changes

This provides various patches sent to the devicetree-compiler mailing list
to enhance the Python bindings. A final version of this patch may be
created once upstreaming is complete, but if it takes too long, this can
act as a placeholder.

New pylibfdt features:
- Support for most remaining, relevant libfdt functions
- Support for sequential-write functions

Changes are applied to existing U-Boot tools as needed.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/dtoc/test_dtoc.py b/tools/dtoc/test_dtoc.py
index 99f4e1a..e475a7e 100644
--- a/tools/dtoc/test_dtoc.py
+++ b/tools/dtoc/test_dtoc.py
@@ -4,7 +4,8 @@
 
 """Tests for the dtb_platdata module
 
-This includes unit tests for some functions and functional tests for
+This includes unit tests for some functions and functional tests for the dtoc
+tool.
 """
 
 import collections