isert-scst: Unbreak the build for kernel versions <= v4.8

Fixes: 36c0648b7e ("isert-scst: Fix the build against kernel v5.3") / r8475.



git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@8482 d57e44dd-8a1f-0410-8b47-8ef2f437770f

iscsi-scst/kernel/isert-scst/iser_rdma.c

@@ -1144,6 +1144,9 @@ out:
 
 static void isert_device_release(struct isert_device *isert_dev)
 {
+#ifndef IB_PD_HAS_LOCAL_DMA_LKEY
+	int err;
+#endif
 	int i;
 
 	TRACE_ENTRY();