stm32: clk: Add 200MHz clock configuration for stm32f746 discovery board

This patch adds 200MHz clock configuration for stm32f746 discovery board.
This patch is based on STM32F4 and emcraft's[1].

[1]:  https://github.com/EmcraftSystems/u-boot

Signed-off-by: Toshifumi NISHINAGA <tnishinaga.dev@gmail.com>
6 files changed