MAGETWO-47800: Sample Data Fix

Author: NadiyaS

app/code/Magento/CatalogSampleData/Model/Product/Gallery.php

@@ -152,7 +152,7 @@ protected function storeImage($product, $images)
                 $table = $imageAttribute->getBackend()->getTable();
                 /** @var \Magento\Framework\DB\Adapter\AdapterInterface $adapter*/
                 $data = [
-                    $attribute->getBackend()->getEntityIdField() => $product->getId(),
+                    $attribute->getEntity()->getLinkField() => $product->getId(),
                     'attribute_id' => $attribute->getId(),
                     'value' => $baseImage,
                 ];