net/sched: act_mirred: Create function tcf_mirred_to_dev and improve readability

[ Upstream commit 16085e48 ]

As a preparation for adding block ID to mirred, separate the part of
mirred that redirect/mirrors to a dev into a specific function so that it
can be called by blockcast for each dev.

Also improve readability. Eg. rename use_reinsert to dont_clone and skb2
to skb_to_send.

Co-developed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Co-developed-by: Pedro Tammela <pctammela@mojatatu.com>
Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 52f671db ("net/sched: act_mirred: use the backlog for mirred ingress")
Signed-off-by: Sasha Levin <sashal@kernel.org>