net/mlx5e: kTLS, Save only the frag page to release at completion

In TX resync flow where DUMP WQEs are posted, keep a pointer to
the fragment page to unref it upon completion, instead of saving
the whole fragment.

In addition, move it the end of the arguments list in tx_fill_wi().

Fixes: d2ead1f3

 ("net/mlx5e: Add kTLS TX HW offload support")
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Reviewed-by: Eran Ben Elisha <eranbe@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>