Source code to create ADC Internal temperature and Vref Calibration function

[hazin]

Source code to create ADC Internal temperature and Vref Calibration function for STM32L152RC dev board.

[TDK]

This is an example which reads the internal temperature sensor and VREFINT channels:

https://github.com/STMicroelectronics/STM32CubeL1/blob/01111760b4100e9948fe29bc399e65fbfca596be/Projects/NUCLEO-L152RE/Examples/ADC/ADC_Sequencer/Src/main.c#L418