board: arm: Add support for Black Pill V1.2 F401CC

Changes:

 - Copied over board files for blackpill_f401ce
 - Changed appropriate soc dtsi from stm32f401Xe.dtsi to stm32f401Xc.dtsi
 - Replaced any instance of F401CE to F401CC
 - Added blackpill_401cc to adc test

In essense the blackpill_f401ce and blackpill_f401cc are the exact
same boards,
the f401cc variant of the stm32 mcu has lesser sram and flash than
the f401ce.

Signed-off-by: Sahaj Sarup <sahaj.sarup@linaro.org>