ext: hal: st: stm32cube: Add HAL for the STM32H7x series

This commit adds the STM32CUBE HAL for STM32H7x series MCUs.

Origin: ST Microelectronics
License: BSD-3-Clause
URL: http://www.st.com/en/embedded-software/stm32cubeh7.html


Commit: 1.4.0
Purpose: HAL layer for STM32H7
Maintained-by: External

Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>