linux-phytec-ti

igc: Fix double definitions

Collision threshold and threshold's shift has been defined twice.
This patch comes to fix that.

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>