[STM32] Rename the f0124 files to f124.

We don't support f0 yet so let's not fool anyone. We may rename those
files back again if when we cross check that it is actually true this
file supports f0.
[STM32F3] Removed F3 specific stuff from the common all header.
[STM32F3] Moved all F3 specific functions out of common.