sched: Provide scaled load information for tasks in /proc

Extend "sched" file in /proc for every task to provide information on
scaled load statistics and percentage-scaled based load (load_avg) for
a task. This will be valuable debug aid.

Change-Id: I6ee0394b409c77c7f79f5b9ac560da03dc879758
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>