drm/i915/debugfs: remove VBT data about DRRS

The debugfs is not the place to print duplicated info about VBT data.

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/20200128151942.2590-1-jani.nikula@intel.com