Revert "sched/fair: set_load_weight() must also call reweight_task() for SCHED_IDLE tasks"

This reverts commit cf0c713c which is
commit d3296052 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: Ia48182ab9aa2b01f4df5dcea4d02cc7a388d633a
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>