The value was determined with the following method:

- take CPUs 1-3 offline
- for each OPP
  - set cpufreq min and max freq to OPP freq
  - start dhrystone benchmark
  - measure CPU power consumption during 10s
  - calculate Cx for OPPx
    - Cx = (Px - P1) / (Vx²fx - V1²f1)          [1]
      using the following units: mW / Ghz / V   [2]
- C = avg(C2, ..., Cn)

[1] see commit 4daa001a ("arm64: dts: juno: Add cpu
     dynamic-power-coefficient information")
[2] https://patchwork.kernel.org/patch/10493615/#22158551

FTR, these are the values for the different OPPs:

freq (kHz)   	mV		Px (mW)		Cx

126000		900		39
216000		900		66		370
312000		900		95		372
408000		900		122		363
600000		900		177		359
696000		950		230		363
816000		1000		297		361
1008000		1050		404		362
1200000		1100		528		362
1416000		1200		770		377
1512000		1300		984		385
1608000		1350		1156		394
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>