arm: ti: am3517_evm: Migrate to OF_UPSTREAM

With the feature of OF_UPSTREAM now available, the device trees
for the SOM and baseboard can now deleted and the device tree
locations need to point to the ti/omap directory.

Signed-off-by: Adam Ford <aford173@gmail.com>

V2:  Remove DT reference from Makefile.
6 files changed