app/testpmd: add TCP flags in flow rules
app/testpmd: add TCP flags in flow rules

This commit adds TCP flags support in flow API as
some drivers have SYN filter.

Signed-off-by: Beilei Xing <7fb7e49de6d75fb4140bfcdada52e66859d93ebd@intel.com>
Tested-by: Wei Zhao <55941fd0e75edbdf274af2cfac8f147525678f08@intel.com>
Acked-by: Adrien Mazarguil <9d39ea493ca46c560334f650ac5d4b5ffbcb5cf0@6wind.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk