15khz output broken with latest commit

[datafux]

The latest commit that enforces VGA scaling breaks 15khz output. IMHO there's no need to enforce scaling. Most of the screenmodes of the Archie support standard PAL signal.
See http://chrisacorns.computinghistory.org.uk/docs/Acorn/Tech/Acorn_A3xA4xVideoSpec.pdf

[sorgelig]

You need to explain what you mean by "broken". I believe core outputs 15KHz to the scaler. Then it's up to HDMI resolution if it will be 15KHz or other frequency.
Archie core uses polynomial clock for pixels which means different pixels have different timings. So on VGA output without scaler you may see pixels of different sizes. Scaler takes care of it.
Originally Archie on MISTer was supposed to be working only on HDMI as VGA output was wrong due to uneven pixels.