This patch causes the TCTL to be explicitly set to fix a problem with
poor network performance (throughput) on certain silicon when configured
for 100M HDX performance.

Cc: Todd Fujinaka <todd.fujinaka@intel.com>
Signed-off-by: NDave Ertman <davidx.m.ertman@intel.com>
Acked-by: NBruce W. Allan <bruce.w.allan@intel.com>
Tested-by: NJeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>