app/testpmd: fix DCB configuration

app/testpmd: fix DCB configuration

An issue is found that DCB cannot be configured on ixgbe
NICs. It's said the TX queue number is not right.
On ixgbe the max TX queue number is not fixed, it depends
on the multi-queue mode.

This patch adds the device configuration before getting
info in the DCB configuration process. So the right info
can be got depending on the configuration.

Fixes: 1a572499 ("app/testpmd: setup DCB forwarding based on traffic class")

Signed-off-by: Wenzhuo Lu <wenzhuo.lu@intel.com>
Acked-by: Bernard Iremonger <bernard.iremonger@intel.com>