Revert "ANDROID: sched: Add vendor hook for util-update related functions"

This reverts commit eb994f27.

The hooks android_rvh_attach_entity_load_avg,
android_rvh_detach_entity_load_avg, android_rvh_update_load_avg,
android_rvh_remove_entity_load_avg, and android_rvh_update_blocked_fair
are not used by any vendor, so remove it to help with merge issues with
future LTS releases.

If they are needed by any real user, it can easily be reverted to add
them back and then the symbols should be added to the abi list at the
same time to prevent it from being removed again later.

Bug: 203756332
Bug: 201260585
Cc: Rick Yiu <rickyiu@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ibb6f0d2b71e830092f8d3452fdf34c5d1975e71e