Add support for the Thermal Sensor/Chip Internal Voltage Monitor/Core
Voltage Monitor (THS/CIVM/CVM) on the Renesas R-Car V4M (R8A779H0) SoC.

The conversion formulas for R-Car V4M are the same as for other R-Car
Gen4 SoCs.

Based on a patch in the BSP by Duy Nguyen.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/bd5b002a802c1e058e0048592f17862db1d04263.1709722342.git.geert+renesas@glider.be