i40e: remove the useless value assignment in i40e_clean_adminq_subtask

The variable ret is overwritten by the following call
i40e_clean_arq_element() and the assignment is useless, so remove it.
Reported-by: Tosk Robot <tencent_os_robot@tencent.com>
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
Tested-by: Tony Brelinski <tonyx.brelinski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/i40e/i40e_main.c

@@ -9842,7 +9842,7 @@ static void i40e_clean_adminq_subtask(struct i40e_pf *pf)
 			dev_dbg(&pf->pdev->dev, "ARQ: Update LLDP MIB event received\n");
 #ifdef CONFIG_I40E_DCB
 			rtnl_lock();
-			ret = i40e_handle_lldp_event(pf, &event);
+			i40e_handle_lldp_event(pf, &event);
 			rtnl_unlock();
 #endif /* CONFIG_I40E_DCB */
 			break;