igc: Remove excess parameter description from igc_is_non_eop

The function description for igc_is_non_eop includes an extra @skb
parameter description. This parameter doesn't exist on the function, so
remove it.

Suggested-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>