subsystem: CPU FREQUENCY DRIVERS- Set cpu_load calculation on current frequency

In timer, cpu_load is calcuated on target_freq.
cpu_load = loadadjfreq / pcpu->target_freq;
But cpu is actually running on current freq i.e. pcpu->policy->cur. So cpu_load
should be calculated on current frequency.
cpu_load = loadadjfreq / pcpu->policy->cur;

Change-Id: I89db6b68e9f82aa52077f6bf7d819dab74265790
Signed-off-by: rahul.khandelwal <rahul.khandelwal@spreadtrum.com>