igc: Use strict cycles for Qbv scheduling

Configuring strict cycle mode in the controller forces more well
behaved transmissions when taprio is offloaded.

When set this strict_cycle and strict_end, transmission is not
enabled if the whole packet cannot be completed before end of
the Qbv cycle.

Fixes: 82faa9b ("igc: Add support for ETF offloading")
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Aravindhan Gunasekaran <aravindhan.gunasekaran@intel.com>
Signed-off-by: Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@intel.com>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/igc/igc_tsn.c

@@ -140,15 +140,8 @@ static int igc_tsn_enable_offload(struct igc_adapter *adapter)
  wr32(IGC_STQT(i), ring->start_time);
  wr32(IGC_ENDQT(i), ring->end_time);
 
- if (adapter->base_time) {
- /* If we have a base_time we are in "taprio"
- * mode and we need to be strict about the
- * cycles: only transmit a packet if it can be
- * completed during that cycle.
- */
- txqctl |= IGC_TXQCTL_STRICT_CYCLE |
- IGC_TXQCTL_STRICT_END;
- }
+ txqctl |= IGC_TXQCTL_STRICT_CYCLE |
+ IGC_TXQCTL_STRICT_END;
 
  if (ring->launchtime_enable)
  txqctl |= IGC_TXQCTL_QUEUE_MODE_LAUNCHT;