This patch adds the support of reset and clock control
block (rcc) found on STM32 SoCs.
This driver is similar to a MFD linux driver.

This driver supports currently STM32H7 only.
STM32F4 and STM32F7 will be migrated to this rcc MFD driver
in the future to uniformize all STM32 SoCs already upstreamed.

Signed-off-by: Christophe Kerello <christophe.kerello@st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Vikas Manocha <vikas.manocha@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>