[dts] L3FWD perf test will be blocked with latest dts

[Xu, Qian Q]

Heng, I guess the bug may be brought by your patch on RSFEC in etgen framework, pls check!

Traceback (most recent call last):
  File "./main.py", line 153, in <module>
    args.debug, args.debugcase)
  File "/root/dts/framework/dts.py", line 501, in run_all
    dts_crbs_init(crbInst, skip_setup, read_cache, project, base_dir, nics, virt                                                               type)
  File "/root/dts/framework/dts.py", line 273, in dts_crbs_init
    tester.init_ext_gen()
  File "/root/dts/framework/tester.py", line 76, in init_ext_gen
    self.ixia_packet_gen = IxiaPacketGenerator(self)
  File "/root/dts/framework/etgen.py", line 158, in __init__
    self.enable_rsfec = ixiaPorts[ixiaRef]['enable_rsfec']
KeyError: 'enable_rsfec'
Error in atexit._run_exitfuncs:
Traceback (most recent call last):
  File "/usr/lib64/python2.7/atexit.py", line 24, in _run_exitfuncs
    func(*targs, **kargs)
  File "/root/dts/framework/dts.py", line 109, in close_all_sessions
    for port_info in dut.ports_info:
TypeError: 'NoneType' object is not iterable
Error in sys.exitfunc:
Traceback (most recent call last):
  File "/usr/lib64/python2.7/atexit.py", line 24, in _run_exitfuncs
    func(*targs, **kargs)
  File "/root/dts/framework/dts.py", line 109, in close_all_sessions
    for port_info in dut.ports_info:
TypeError: 'NoneType' object is not iterable

Thanks
Qian