ARM: dts: AM571x-IDK Initial Support

The AM571x-IDK board is a board based on TI's AM5718 SOC
which has a single core 1.5GHz A15 processor. This board is a
development platform for the Industrial market with:
- 1GB of DDR3L
- Dual 1Gbps Ethernet
- HDMI,
- PRU-ICSS
- uSD
- 16GB eMMC
- CAN
- RS-485
- PCIe
- USB3.0
- Video Input Port
- Industrial IO port and expansion connector

The link to the data sheet and TRM can be found here:

http://www.ti.com/product/AM5718



Initial support is only for basic peripherals.

Signed-off-by: Schuyler Patton <spatton@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>