net/mlx5: fix function documentation

tso and vlan parameters were removed from the signature
of txq_mbuf_to_swp function.

The documentation of the function was not updated accordingly.

Remove the tso and vlan documentation to match the function signature.

Fixes: 8f6d9e13a98c ("net/mlx5: remove redundant checks")
Cc: stable@dpdk.org
Signed-off-by: Asaf Penso <asafp@mellanox.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>