thermal: sti: Add support for ST's Memory Mapped based Thermal controller

This is the traditional way of obtaining a device driver's register
address space.  The aim of this driver is to supply controller specific
information to the ST Thermal Core.

Signed-off-by: Ajit Pal Singh <ajitpal.singh@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>