Update VBT defs to reflect revision 216. While at it, default the
expected child device struct size to sizeof the size rather than a
hardcoded value.

v2: Fix bit order (David)

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180118153310.32437-1-jani.nikula@intel.com