net/i40e: replace license text with SPDX tag
net/i40e: replace license text with SPDX tag

Signed-off-by: Xiaolong Ye <c7d6fc2f7e22da80deb234d523238b510a8c0f08@intel.com>
Acked-by: Bruce Richardson <66b9e8e8fbd5e9f41f91b0af050876182ce9d0e4@intel.com>

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