i40e: add missing kernel-doc argument

The following kernel-doc arguments for their respective functions are
missing:

1) @cd_type_cmd_tso_mss for i40e_tso();
2) @cd_type_cmd_tso_mss for i40e_tsyn();
3) @tx_ring for i40e_tx_enable_csum().

Add them all for the kernel-doc requirement.

Signed-off-by: Jean Sacren <sakiwit@gmail.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Acked-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>