drm/nouveau/disp/nv50-: force scaler for any non-default LVDS/eDP modes

Higher layers tend to add a lot of modes not actually in the EDID, such
as the standard DMT modes. Changing this would be extremely intrusive to
everyone, so just force the scaler more often. There are no practical
cases we're aware of where a LVDS/eDP panel has multiple resolutions
exposed, and i915 already does it this way.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110660


Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>