This patch adds a reset controller implementation for STMicroelectronics
STi family SoCs; it allows a group of related reset like controls found
in multiple system configuration registers to be represented by a single
controller device.
Driver code has been mainly extracted from kernel
drivers/reset/sti/reset-stih407.c
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>