desk.cpl: Font size list in advanced settings dialog is empty

The patch executes the font size enum loop regardless of the success of RegOpenKeyEx(),
so the user don't get an empty list in case the opened key doesn't exist.

Also changing the querried value under the key used by desk.cpl from ReactOS has no effect
on desk.cpl from Windows. Instead it seems to querry for the same value under
"SYSTEM\CurrentControlSet\Hardware Profiles\Current\Software\Fonts". But I'm not sure if this
is intended, so I don't touch the key path.

I am not sure if this qualifies as bug, so I can change it if desired.