arm64: dts: sdm845: wireup the thermal trip points to cpufreq

Since all cpus in the big and little clusters, respectively, are in the
same frequency domain, use all of them for mitigation in the
cooling-map. We end up with two cooling devices - one each for the big
and little clusters.
Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>
Acked-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Andy Gross <andy.gross@linaro.org>