ARM: dts: msm: Update silver CPUs's idle cost data for SDM845v2

The silver CPUs's idle cost data is higher than non-idle energy
cost at lower frequency range. This due to not updating idle
cost data when energy model is updated for SDM845v2. Fix this
lowering the idle cost data for silver CPUs.

Change-Id: I7bbc550a470255f134f6b430e8491f54eec8b9d5
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>