act_mirred: clear sender cpu before sending to tx

Similar to commit c29390c6 ("xps: must clear sender_cpu before forwarding")
the skb->sender_cpu needs to be cleared when moving from Rx
Tx, otherwise kernel could crash.

Fixes: 2bd82484 ("xps: fix xps for stacked devices")
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <cwang@twopensource.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>