net/mlx5: add header reformat HW steering action

net/mlx5: add header reformat HW steering action

HW steering header reformat action can work under bulk mode. In
this case, when create the table, bulk size of header reformat
actions will be allocated in low level. Afterwards, when create
flow, just simply specify the action index in the bulk and the
encapsulation data to the action will be enough.

Signed-off-by: Suanming Mou <suanmingm@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>