app/testpmd: update Rx offload after setting MTU

app/testpmd: update Rx offload after setting MTU

Currently, Rx offload capabilities and max_rx_pkt_len in the struct
variable named rte_port are not updated after setting mtu successfully
in port_mtu_set function by 'port config mtu <port_id> <value>' command.
This may lead to reconfig mtu to the initial value in the driver when
recalling rte_eth_dev_configure API interface.

This patch updates Rx offload capabilities and max_rx_pkt_len after
setting mtu successfully when configuring mtu.

Fixes: ae03d0d18adf ("app/testpmd: command to configure MTU")
Cc: stable@dpdk.org
Signed-off-by: Huisong Li <lihuisong@huawei.com>
Signed-off-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>