cpufreq_stats: Adds the fucntionality to load current values for each frequency

for all the cores.

The current values for the cpu cores needs to be added to the device
tree for this functionaly to work. It loads the current values for each
frequecy in uA for all the cores.

Change-Id: If03311aaeb3e4c09375dd0beb9ad4fbb254b5c08
Signed-off-by: Ruchi Kandoi <kandoiruchi@google.com>