ixgbe: remove redundant configuration of tx_sample_rate

This change fixes a minor redundancy in that tx_sample_rate was set twice.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>