dpdk.c: skip printing port stats when log_level <= DEBUG
dpdk.c: skip printing port stats when log_level <= DEBUG

megahall/sdn_sensor,megahall/sdn_sensor,TidyHuang/sdn_sensor,TidyHuang/sdn_sensor,TidyHuang/sdn_sensor,TidyHuang/sdn_sensor,TidyHuang/sdn_sensor,megahall/sdn_sensor,megahall/sdn_sensor,megahall/sdn_sensor,TidyHuang/sdn_sensor,megahall/sdn_sensor,TidyHuang/sdn_sensor,megahall/sdn_sensor,TidyHuang/sdn_sensor,megahall/sdn_sensor