net: hns3: minor cleanup for hns3_handle_rx_bd()

Since commit e5597095 ("net: hns3: Add handling of GRO Pkts
not fully RX'ed in NAPI poll"), ring->skb is used to record the
current SKB when processing the RX BD in hns3_handle_rx_bd(),
so the parameter out_skb is unnecessary.

This patch also adjusts the err checking to reduce duplication
in hns3_handle_rx_bd(), and "err == -ENXIO" is rare case, so put
it in the unlikely annotation.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>