sched/walt: Move scheduler techpack to kernel

The scheduler techpack sources are moved to kernel to ease
the development.

The weak symbol definitions for WALT functions are no longer
required to cover the case of compiling kernel without syncing
the scheduler techpack. So remove all the weak symbol references.

Change-Id: Ief85bccd3dceaf60dda44aef9893b4138dc63380
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>