net: hns3: modify type of pull_len in struct hns3_enet_ring

driver inclusion
category: bugfix
bugzilla: NA
CVE: NA

pull_len gets value from eth_get_headlen(), which always returns u32. So
it's better to change its type from int to u32.

Feature or Bugfix: Bugfix
Signed-off-by: Nliweihang <liweihang@huawei.com>
Reviewed-by: Nlipeng <lipeng321@huawei.com>
Reviewed-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/net/ethernet/hisilicon/hns3/hns3_enet.h

@@ -417,7 +417,7 @@ struct hns3_enet_ring {
 	 */
 	int next_to_clean;
 
-	int pull_len;
+	u32 pull_len;
 	u32 frag_num;
 	unsigned char *va;