Android O IOT Preview 6 (4475743)
Update dtc to the version of 20170713 of upstream

For pylibfdt, merge dtc to upstream 0016f8c2aa32423f680ec6e94a00f1095b81b5fc
and merge history

Bug: 64424046
Test: Build dtc, use output dtc to build dts, can output correct dtb.
Change-Id: I4304259e1245bc4a45d0b8f8e3ae8119e509042c