While converting sch_sfq to use timer_setup(), the commit cdeabbb8
("net: sched: Convert timers to use timer_setup()") forgot to
initialize the 'sch' field. As a result, the timer callback tries to
dereference a NULL pointer, and the kernel does oops.

Fix it initializing such field at qdisc creation time.

Fixes: cdeabbb8 ("net: sched: Convert timers to use timer_setup()")
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Acked-by: NCong Wang <xiyou.wangcong@gmail.com>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>