net/i40e: sync between x86 and arm64 vector PMD
net/i40e: sync between x86 and arm64 vector PMD

Porting two changes from x86 SSE implematation.
    net/i40e: fix checksum flag in x86 vector Rx
    net/i40e: eliminate mbuf write on rearm

Signed-off-by: Jianbo Liu <ad48e27d4475ec2c10ba93ba465af79f05639344@linaro.org>

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