rocker: add apply action to copy pkt to CPU

For term_mac tbl, we'll send IPv4/IPv6 multicast router pkts to CPU for
processing, so add flow table apply action "copy_to_cpu".  Can also be used for
bridging and ACL tbls, but currently only used for term_mac tlb to send router
multicast pkts up to Linux for processing.

Signed-off-by: Scott Feldman <sfeldma@gmail.com>