Change Enable HQ scalers above setting steps from 10% to 1%

As a result of conversation starting at post #49 here: http://forum.xbmc.org/showthread.php?tid=170855&page=5

With 1% steps it is quite a bit more work to reach 100%, but a large value can still be entered directly with keyboard (and I guess with remote too - cannot test since I have no remote).