Add an Operating Performance Points table for the CPU cores to enable
Dynamic Voltage & Frequency Scaling (DVFS) on the H616.
The values were taken from the BSP sources. There is a separate OPP set
seen on some H700 devices, but they didn't really work out in testing, so
they are not included for now.

Also add the needed cpu_speed_grade nvmem cell and the cooling cells
properties, to enable passive cooling.
Signed-off-by: Martin Botka <martin.botka@somainline.org>
[Andre: rework to minimise opp-microvolt properties]
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>