defconfig: introduce d855 defconfig
HACK: Workaround for broken camera driver

 * VENUS_BUFFER_SIZE is inlined all over userspace, including in the
   camera driver. The camera driver is ancient, and referenced the
   old calculation which does not include the 8K of padding for
   extradata.
 * Return zero here, so the padding is not included across userspace.
   This will fix the camera, but break several new video features.

 * This issue is a STOPSHIP and must be resolved before final release.

Change-Id: I9e02bd606ececafa13edcf476a261ef7ad39a710