hw/block/nvme: destroy request iov before reuse

Make sure the request iov is destroyed before reuse; fixing a memory
leak.

Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
Reviewed-by: Minwoo Im <minwoo.im.dev@gmail.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>

hw/block/nvme.c

@@ -569,6 +569,10 @@ static void nvme_rw_cb(void *opaque, int ret)
     if (req->qsg.nalloc) {
         qemu_sglist_destroy(&req->qsg);
     }
+    if (req->iov.nalloc) {
+        qemu_iovec_destroy(&req->iov);
+    }
+
     nvme_enqueue_req_completion(cq, req);
 }