net/i40e: handle QinQ strip
net/i40e: handle QinQ strip

Qinq strip is not supported by i40e. When user tries to turn on
QinQ strip, the driver gives unsupported return value and log.

Signed-off-by: Tao Zhu <98fc9452bad001bbed4b53169990d94b082d6178@intel.com>
Acked-by: Beilei Xing <7fb7e49de6d75fb4140bfcdada52e66859d93ebd@intel.com>
Reviewed-by: Xiaolong Ye <c7d6fc2f7e22da80deb234d523238b510a8c0f08@intel.com>

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