arm: dts: am3517_evm: Sync DTS files with Linux 4.13-RC5

To keep the DTS and DTSI files clean and in sync with Linux, new
u-boot.dtsi files are added.

There are some spacing issues in the patch, but they appear to be
present in the Linux source files.  I'll try to get to fixing them there,
and do a future re-sync at a later date.

Signed-off-by: Adam Ford <aford173@gmail.com>
Tested-by: Derald D. Woods <woods.technical@gmail.com>