arm64: dts: juno-r2: add dynamic-power-coefficient properties

Taken from commit cadf54148974 "arm64: dts: Add IPA parameters to soc
thermal zone" wich also sets up SoC thermal zones and bind them to
cpufreq cooling devices. We don't want this functionality right now.

The commit is for example part of:

git.linaro.org/landing-teams/working/arm/kernel-release.git
lt_arm/ack-4.9-armlt-18.01

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>