drm/i915: disable all display features when no display

Disable all display feature flags when there are no pipes i.e. there is
no display. This should help with not having to additionally check for
HAS_DISPLAY() when a feature flag check would suffice.

Also disable modeset and atomic driver features.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200910095227.9466-1-jani.nikula@intel.com