dts: arm: ti: Remove use of CONFIG_SOC_* from TI SoC dts files

To move forward and remove use of Kconfig in dts files lets just create
SoC specific dtsi files that the boards can include.  This lets us
remove:

CONFIG_SOC_CC3220SF
CONFIG_SOC_MSP432P401R

Signed-off-by: Kumar Gala <kumar.gala@linaro.org>