sched: tg->se->load should be initialised to tg->shares

sched: tg->se->load should be initialised to tg->shares

Michael reported that when enable autogroup on UP, system
responsiveness becomes very bad.
Because in init_tg_cfs_entry() we initialise se->load
to 0 instead of tg->shares, in the end we have 0-weight
sched entity on rq, then lead to misbehavior.

Reported-by: Michael Witten <mfwitten@gmail.com>
Reported-by: Christian Kujau <christian@nerdbynature.de>
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Signed-off-by: Andy Whitcroft <apw@canonical.com>