libfdt is part of the device tree support in scripts/dtc/libfdt. For
some platforms that use the Device Tree, we want to be able to edit
the flattened device tree form.

We don't want to burden kernel builds that do not require it, so we
gate compilation of libfdt files with CONFIG_LIBFDT. So if it is
needed, you need to do this in your Kconfig:

select LIBFDT

And in the Makefile of the code using libfdt something like:

ccflags-y := -I$(src)/../../../scripts/dtc/libfdt

Signed-off-by: David Daney
Cc: linux-mips@linux-mips.org
Cc: devicetree-discuss@lists.ozlabs.org
Cc: Grant Likely
Cc: linux-kernel@vger.kernel.org
Acked-by: Rob Herring
Signed-off-by: Ralf Baechle