Show the correct subtotal amount for partial creditmemos

Author: kassner

app/code/Magento/Sales/view/frontend/templates/email/items/creditmemo/default.phtml

@@ -31,6 +31,6 @@
     </td>
     <td class="item-qty"><?= /* @escapeNotVerified */  $_item->getQty() * 1 ?></td>
     <td class="item-price">
-        <?= /* @escapeNotVerified */  $block->getItemPrice($_item->getOrderItem()) ?>
+        <?= /* @escapeNotVerified */  $block->getItemPrice($_item) ?>
     </td>
 </tr>