net/i40e: convert to SPDX license tag
net/i40e: convert to SPDX license tag

Signed-off-by: Gavin Hu <207ee22c2cf71e20c5b5df8395050c07c07d8709@linaro.org>
Acked-by: Hemant Agrawal <90d96ef1ecd8ed49b97c7897be950e80824a9c5c@nxp.com>
Acked-by: Ferruh Yigit <ba8734c3c506d2e3557bd4ac8fdaccd25bdb9aa7@intel.com>

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