sched/core: fix bug when moving a domain between cpupools

sched/core: fix bug when moving a domain between cpupools

For each UNIT, sched_set_affinity is called before unit->priv is updated
to the new cpupool private UNIT data structure. The issue is
sched_set_affinity will call the adjust_affinity method of the cpupool.
If defined, the new cpupool may use unit->priv (e.g. credit), which at
this point still references the old cpupool private UNIT data structure.

This change fixes the bug by moving the switch of unit->priv earler in
the function.

Signed-off-by: Jeff Kubascik <jeff.kubascik@dornerworks.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Acked-by: Dario Faggioli <dfaggioli@suse.com>