Fix stale bandwidth-by-IP table entries

When the number of valid rows in the table reduced by more than 1 between updates, stale entries were left displayed at the end - e.g. 8 rows (0-7), then next update has only 5 rows (0-4). Row 5 is hidden but rows 6 and 7 remain displayed.
This "feature" looks like it has been around ever since this module was first added.
Should fix http://forum.pfsense.org/index.php/topic,59714.msg321414.html#msg321414
The functional change is making a single "if" test at line 156/157 and the removed "}" at 181. The rest of the diff listing is just changes due to code indenting.