Makefile: Don't overwrite DDEFS.
SC STM32F4: Add support for LSM9DS0 minicap

This patch includes the following changes:
* Add pin defines for LSM9DS0 minicap.
* Do full pinmuxin for LSM9DS0 minicap in init.
* Properly use SC_HAS_* instead of SC_USE_*
* Enable I2C2 instead of 3 for SC STM32F4 board.