net: hns3: fix length overflow when CONFIG_ARM64_64K_PAGES

When enable the config item "CONFIG_ARM64_64K_PAGES", the size of PAGE_SIZE
is 65536(64K). But the type of length is u16, it will overflow. So change it
to u32.
Signed-off-by: NTan Xiaojun <tanxiaojun@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

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

@@ -288,7 +288,7 @@ struct hns3_desc_cb {
 	u16 page_offset;
 	u16 reuse_flag;
 
-	u16 length;     /* length of the buffer */
+	u32 length;     /* length of the buffer */
 
        /* desc type, used by the ring user to mark the type of the priv data */
 	u16 type;