igc: Remove unneeded variable

Though we are populating and tracking ictxqec, the value is not being used
for anything so remove it altogether and save the register read.

Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>