drm/i915/sdvo: Don't add DDC modes for LVDS

Stop enumerating the DDC modes for SDVO LVDS outputs (outside
the initial fixed mode setup). intel_panel_mode_valid() will
just reject most of them anyway, and any left over are entirely
pointless as they'll match the fixed mode hdisp+vdisp+vrefresh
so no user visible effect from using them instead of the fixed
mode.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221026101134.20865-6-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>