net/sched: act_mirred: Rename tcfm_ok_push to tcfm_mac_header_xmit and make it a bool

'tcfm_ok_push' specifies whether a mac_len sized push is needed upon
egress to the target device (if action is performed at ingress).

Rename it to 'tcfm_mac_header_xmit' as this is actually an attribute of
the target device (and use a bool instead of int).

This allows to decouple the attribute from the action to be taken.

Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>