Converted over all STM32F4 based boards to use device tree and removed
associated bits that now come from the device tree for STM32F4.
Boards that are now using devicetree:
* 96b_carbon
* nucleo f401re
* nucleo f411re
Change-Id: Ibe197ca0a3f5ad78d594485a578d986403cc824a
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>