buildinfo: only set ro.build.product on non-unified devices

echo "ro.wifi.channels=$PRODUCT_DEFAULT_WIFI_CHANNELS"

echo "ro.board.platform=$TARGET_BOARD_PLATFORM"

if [ "$TARGET_UNIFIED_DEVICE" == "" ] ; then

  echo "# ro.build.product is obsolete; use ro.product.device"

  echo "ro.build.product=$TARGET_DEVICE"

if [ "$TARGET_UNIFIED_DEVICE" == "" ] ; then

  echo "ro.product.model=$PRODUCT_MODEL"

  echo "ro.product.device=$TARGET_DEVICE"

  echo "# Do not try to parse description, fingerprint, or thumbprint"