ARM: davinci: da850: add SoC DT data

Add DT data for DA850 SoC. Only interrupt controller and
serial port information is being added at this time.

Signed-off-by: Heiko Schocher <hs@denx.de>
[nsekhar@ti.com: refactored DT data into SoC specific and
board specific and include SoC data into .dtsi file]
Signed-off-by: Sekhar Nori <nsekhar@ti.com>