cpufreq: interactive: Fix load in cpufreq_interactive_cpuload event

CPU load is now normalized to per-policy target_load, instead of
current frequency of CPU. Fix cpufreq_interactive_cpuload accordingly
so that its load number matches other cpufreq interactive events like
cpufreq_interactive_target/notyet/already.

Change-Id: I0685b5930ad1bac01819e96fcdfc181167d4dae0
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>