drm/i915: Update VBT fields for child devices

This patch adds new fields that are not yet added in drm code
in child devices struct

Signed-off-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Signed-off-by: Durgadoss R <durgadoss.r@intel.com>
Signed-off-by: Shubhangi Shrivastava <shubhangi.shrivastava@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459420907-11383-1-git-send-email-shubhangi.shrivastava@intel.com