e1000: Use time_after() for time comparison

To be future-proof and for better readability the time comparisons are modified
to use time_after() instead of plain, error-prone math.
Signed-off-by: Manuel Schölling <manuel.schoelling@gmx.de>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/e1000/e1000_ethtool.c

@@ -1460,7 +1460,8 @@ static int e1000_run_loopback_test(struct e1000_adapter *adapter)
 			 * enough time to complete the receives, if it's
 			 * exceeded, break and error off
 			 */
-		} while (good_cnt < 64 && jiffies < (time + 20));
+		} while (good_cnt < 64 && time_after(time + 20, jiffies));
+
 		if (good_cnt != 64) {
 			ret_val = 13; /* ret_val is the same as mis-compare */
 			break;