sched: report group load to the cpufreq

Group load contains the CPU load corresponding to colocated tasks.
This load is tracked separately from the non-colocated tasks that
form part of the runqueue prev_runnable_sum. Report the sum of
grouped and non grouped load to cpufreq so that frequency can be
set properly based on total load.

Change-Id: I685a41cbe53dca578caec69376c276f5cf480d45
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>