For i40e Tx path, use bulk free of the buffers when mbuf fast free
mode is enabled. This can efficiently improve the performance.

v2:
1. fix bug when tx_rs_thres > RTE_I40E_TX_MAX_FREE_BUF_SZ (Beilei)

v3:
1. change variable name for more readable (Beilei)

Feifei Wang (2):
  net/i40e: improve performance for scalar Tx
  net/i40e: improve performance for vector Tx

 drivers/net/i40e/i40e_rxtx.c            | 30 ++++++++++++++++++++-----
 drivers/net/i40e/i40e_rxtx_vec_common.h | 11 +++++++++
 2 files changed, 35 insertions(+), 6 deletions(-)

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2.25.1