sfc: attach an MAE counter to TC actions that need it

The only actions that expect stats (that sfc HW supports) are gact shot
 (drop), mirred redirect and mirred mirror.  Since these are 'deliverish'
 actions that end an action-set, we only require at most one counter per
 action-set.

Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>