SCons: PlatformTools: hand defines form device file to envOld

This handes the defines extracted from the device file
e.g. STM32F3XX to the "envOld" which is the environment
used to build the project files.
Ext: CMSIS: STM32F3: fixed bit defines

See STM32F3 Reference Manual page 115
Uart: STM32: clean up UartHAL code