Converted over all STM32F3 based boards to use device tree and removed
associated bits that now come from the device tree for STM32F3.
Boards that are now using devicetree:
* Nucleo f334r8
* STM32373C Eval
Change-Id: I081a1d83f86e417a98b6864c745354b6b32953b7
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>