ARM: dts: sdm845: reduce unrealistically high CPU idle energy

Current big cluster's idle energy cost is higher than non-idle energy
cost in few frequency steps so that prevents big cluster CPUs from
going into idle.  Lower idle costs to be less than non-idle energy
cost.

Change-Id: Id4eb4fdaea198c531ed1afc2f0915c480480e25b
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>