Fix mdk5 building

1. Delete trailing whitespace for tools/builing.py, tools/keil.py.
2. Add mdk building for the following bsp:
     stm32f0x, stm32f107, stm32f10x, stm32f20x, stm32f40x.

you can use the command for building mdk5 project
scons --target=mdk5