d3296052 ("sched/fair: set_load_weight() must also call reweight_task()
for SCHED_IDLE tasks") applied to sched/core changes how reweight_task() is
called causing conflicts with e83edbf8 ("sched: Add
sched_class->reweight_task()"). Resolve the conflicts by taking
set_load_weight() changes from d3296052 and updating
sched_class->reweight_task() to take pointer to struct load_weight instead
of int prio.

Signed-off-by: Tejun Heo<tj@kernel.org>