ANDROID: Sched: Add vendor hooks in scheduler

These vendor hooks in scheduler are needed to implement Qualcomm's
proprietary load tracking scheme, WALT via vendor modules.

This reverts commit fd1fba66 ("Revert "ANDROID: Sched: Add hooks for
scheduler"") to bring back the original change 99545883 ("ANDROID:
Sched: Add hooks for scheduler"). The original change was reverted to
facilitate upstream merges. This revert modifies the original change to
fit into the current mainline.

Bug: 200103201
Bug: 234483895
Change-Id: I9c56ab9044d1d68c007ea9e2279c7dd966502e94
Signed-off-by: Sai Harshini Nimmala <quic_snimmala@quicinc.com>