Import libfdt v1.4.1

Imports libfdt code from https://git.kernel.org/cgit/utils/dtc/dtc.git
tag "v1.4.1" commit 302fca9f4c283e1994cf0a5a9ce1cf43ca15e6d2.

Change-Id: Ia0d966058beee55a9047e80d8a05bbe4f71d8446
diff --git a/lib/libfdt/TODO b/lib/libfdt/TODO
new file mode 100644
index 0000000..288437e
--- /dev/null
+++ b/lib/libfdt/TODO
@@ -0,0 +1,3 @@
+- Tree traversal functions
+- Graft function
+- Complete libfdt.h documenting comments