drm/i915: Use intel_panel_mode_valid() for DSI/LVDS/(s)DVO

drm/i915: Use intel_panel_mode_valid() for DSI/LVDS/(s)DVO

All fixed mode panels should behave the same way when it comes to mode
filtering. Reuse the intel_panel_mode_valid() for all of them.

This changes the behaviour to match what we do for eDP, ie.
reject anything that doesn't exactly match the fixed mode
dimensions. Users can still manually provide different
sized modes which will be handled by the panel fitter just
as before. The difference is that we can no longer report
funny modes in the connector's mode list.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210923200109.4459-3-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>