net/sched: Refactor qdisc_graft() for ingress and clsact Qdiscs

[ Upstream commit 2d5f6a8d7aef7852a9ecc555f88c673a1c91754f ]

Grafting ingress and clsact Qdiscs does not need a for-loop in
qdisc_graft().  Refactor it.  No functional changes intended.

Tested-by: Pedro Tammela <pctammela@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Vlad Buslov <vladbu@nvidia.com>
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Stable-dep-of: 84ad0af0bccd ("net/sched: qdisc_destroy() old ingress and clsact Qdiscs before grafting")
Signed-off-by: Sasha Levin <sashal@kernel.org>