cpufreq: schedutil: Make the code consistent across 1 vs many CPU/policy

The code for 1 CPU per policy also gets exercised on a multi CPU per policy
system if all but one CPU in a policy are hotplugged out. So, make sure the
code for these two cases remain consistent even though the 1 CPU per policy
code rarely gets exercised is a multi CPU per policy system.

Change-Id: Ib372fb893206dc1ee88d2dd0aeb2bd2cc96ac955
Signed-off-by: Saravana Kannan <skannan@codeaurora.org>