dtc: Use the same endian-conversion functions as libfdt

[Jon Loeliger]

> Currently both libfdt and dtc define a set of endian conversion macros
> for accessing the device tree blob which is always big-endian.  libfdt
> uses names like cpu_to_fdt32() and dtc uses names like cpu_to_be32 (as
> the Linux kernel).  This patch switches dtc over to using the libfdt
> macros (including libfdt_env.h to supply them).  This has a couple of
> small advantages:
> 	- Removes some code duplication
> 	- Will make conversion a bit easier if we ever need to produce
>           little-endian device tree blobs.
> 	- dtc no longer needs to pull in netinet/in.h simply for the
>           ntohs() and ntohl() functions
> 
> Signed-off-by: David Gibson <david at gibson.dropbear.id.au>

Applied.

jdl