net/hns3: fix packets offload features flags in Rx

net/hns3: fix packets offload features flags in Rx

Currently there is a certain probability of the unexpected ol_flag of
the Rx packets's rte_mbuf when receiving packets.

The root cause as below:
1. The member variable named ol_flag of the structure named rte_mbuf is
   not properly initialized to zero in the '.rx_pkt_burst' ops
   implementation function named hns3_recv_pkts.
2. When multi-segment rte_mbufs are needed for long packet in Rx
   operation, the driver should assign value to the ol_flag of the first
   segment, not to the ol_flag of the last segment.

This patch fixes it with the following modification in the
'.rx_pkt_burst' ops implementation function named hns3_recv_pkts.
1. Where the first write operation in the '.rx_pkt_burst' ops
   implementation function, assign PKT_RX_RSS_HASH to ol_flags directly
   using '=' operation instead of '|=' operation.
2. In the static function named hns3_rx_set_cksum_flag, the last
   rte_mbuf's ol_flags should be assigned when processing multi-segment.
   We fix it by passing first_seg variable to the function instead of
   rxm(the last segment's address).

Fixes: bba636698316 ("net/hns3: support Rx/Tx and related operations")
Fixes: ad7cf94823e8 ("net/hns3: fix offload flag for RSS hash")
Cc: stable@dpdk.org
Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
Signed-off-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>