app/testpmd: fix DCB re-configuration

app/testpmd: fix DCB re-configuration

After DCB mode is configured, if we decrease the number of RX and TX
queues, fwd_config_setup() will be called to setup the DCB forwarding
configuration. And forwarding streams are updated based on new queue
numbers in fwd_config_setup(), but the mapping between the TC and
queues obtained by rte_eth_dev_get_dcb_info() is still old queue
numbers (old queue numbers are greater than new queue numbers).
In this case, the segment fault happens. So rte_eth_dev_configure()
should be called again to update the mapping between the TC and
queues before rte_eth_dev_get_dcb_info().

Like:
set nbcore 4
port stop all
port config 0 dcb vt off 4 pfc on
port start all
port stop all
port config all rxq 8
port config all txq 8

Fixes: 900550de04a7 ("app/testpmd: add dcb support")
Cc: stable@dpdk.org
Signed-off-by: Huisong Li <lihuisong@huawei.com>
Signed-off-by: Lijun Ou <oulijun@huawei.com>
Acked-by: Xiaoyun Li <xiaoyun.li@intel.com>