app/testpmd: enable queue ring size configure

Add command to change specific queue's ring size configure,
the new value will only take effect after command that restart
the device(port stop <port_id>/port start <port_id>) or command
that setup the queue(port <port_id> rxq <qid> setup) at runtime.

Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
Acked-by: Ferruh Yigit <ferruh.yigit@intel.com>