net_sched: avoid casting void pointer

tp->root is a void* pointer, no need to cast it.

Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc net/sched/cls_basic.c
Simple merge

diff --cc net/sched/cls_fw.c
Simple merge

diff --cc net/sched/cls_route.c
Simple merge

diff --cc net/sched/cls_tcindex.c
Simple merge

diff --cc net/sched/cls_u32.c
Simple merge