staging: qlge: change msleep to usleep_range

This patch changes msleep() to usleep_range() based on
Documentation/timers/timers-howto.txt. It suggests using usleep_range()
for small msec(1ms - 20ms) because msleep() will often sleep longer than
the desired value. Issue found by checkpatch.
Signed-off-by: Tobias Alam <tobiasalam@gmail.com>
Link: https://lore.kernel.org/r/YMa60p5dl0LMV/9D@tobias-VirtualBoxSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/qlge/qlge_ethtool.c

@@ -553,7 +553,7 @@ static int qlge_run_loopback_test(struct qlge_adapter *qdev)
 		atomic_inc(&qdev->lb_count);
 	}
 	/* Give queue time to settle before testing results. */
-	msleep(2);
+	usleep_range(2000, 2100);
 	qlge_clean_lb_rx_ring(&qdev->rx_ring[0], 128);
 	return atomic_read(&qdev->lb_count) ? -EIO : 0;
 }