gve: Fix error return code in gve_prefill_rx_pages()

If alloc_page() fails in gve_prefill_rx_pages(), it should return
an error code in the error path.

Fixes: 82fd151d ("gve: Reduce alloc and copy costs in the GQ rx path")
Cc: Jeroen de Borst <jeroendb@google.com>
Cc: Catherine Sullivan <csully@google.com>
Cc: Shailend Chand <shailend@google.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/google/gve/gve_rx.c

@@ -150,8 +150,10 @@ static int gve_prefill_rx_pages(struct gve_rx_ring *rx)
 		for (j = 0; j < rx->qpl_copy_pool_mask + 1; j++) {
 			struct page *page = alloc_page(GFP_KERNEL);
 
-			if (!page)
+			if (!page) {
+				err = -ENOMEM;
 				goto alloc_err_qpl;
+			}
 
 			rx->qpl_copy_pool[j].page = page;
 			rx->qpl_copy_pool[j].page_offset = 0;