net/i40e: remove redundant reset operation
net/i40e: remove redundant reset operation

For free buffer operation in i40e vector path, it is unnecessary to
store 'NULL' into txep.mbuf. This is because when putting mbuf into Tx
queue, tx_tail is the sentinel. And when doing tx_free, tx_next_dd is
the sentinel. In all processes, mbuf==NULL is not a condition in check.
Thus reset of mbuf is unnecessary and can be omitted.

Signed-off-by: Feifei Wang <2493857810266eaae720c9869c8b9d6ce45d3739@arm.com>
Reviewed-by: Ruifeng Wang <a548d51fbc42485a8ba807711a537e88c2b59dd2@arm.com>
Acked-by: Qi Zhang <9e9e58ffa71a29bb7b87766b362515be648fcbe0@intel.com>

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