sched/walt: Consolidate WALT parameters

Create specific structures to hold all WALT related parameters used in the
scheduler.
This is to separate WALT functionality from scheduler code for GKI
purposes.

Change-Id: I6013883c00f2089dba3e5d0890c9abf5f57b3da6
Signed-off-by: Sai Harshini Nimmala <snimmala@codeaurora.org>