i40e/i40evf: save aq writeback for future inspection

Add the ability to save the AdminQ write back descriptor if a
caller supplies a buffer for it to be saved into.

Change-ID: I3d1301d26360b39a2d66dc8569e851f54133a3af
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/i40evf/i40e_adminq.c b/drivers/net/ethernet/intel/i40evf/i40e_adminq.c
index f08450b..15c8ac8 100644
--- a/drivers/net/ethernet/intel/i40evf/i40e_adminq.c
+++ b/drivers/net/ethernet/intel/i40evf/i40e_adminq.c
@@ -830,6 +830,10 @@
 	i40evf_debug_aq(hw, I40E_DEBUG_AQ_COMMAND, (void *)desc, buff,
 			buff_size);
 
+	/* save writeback aq if requested */
+	if (details->wb_desc)
+		*details->wb_desc = *desc_on_ring;
+
 	/* update the error if time out occurred */
 	if ((!cmd_completed) &&
 	    (!details->async && !details->postpone)) {