net/mlx5e: Allow re-allocating mod header actions

Currently the size of the mod header actions array is deduced from the
number of parsed TC header rewrite actions. However, mod header actions
are also used for setting HW register values. Support the dynamic
reallocation of the mod header array as a pre-step for adding HW
registers mod actions.

Signed-off-by: Paul Blakey <paulb@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Oz Shlomo <ozsh@mellanox.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>