hal: stm32f2x: Add HAL for the STM32F2x series

This adds the HAL code needed for the SoC for the stm32f2 series.

Origin: ST Microelectronics
License: BSD-3-Clause
URL: http://www.st.com/en/embedded-software/stm32cubef2.html


Commit: 1.7.0
Purpose: HAL layer for stm32f2
Maintained-by: External

Signed-off-by: qianfan Zhao <qianfanguijin@163.com>