ixgbe: remove unneeded ipsec test in TX path

Since the ipsec data fields will be zero anyway in the non-ipsec
case, we can remove the conditional jump.

Suggested-by: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: Shannon Nelson <shannon.nelson@oracle.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>