net/hns3: support Tx push quick doorbell for performance

net/hns3: support Tx push quick doorbell for performance

Kunpeng 930 support Tx push mode which could improve performance.
It works like below:
 1. Add PCIe bar45 which support driver direct write the Tx descriptor
    or tail reg to it.
 2. Support three operations: a) direct write one Tx descriptor, b)
    direct write two Tx descriptors, c) direct write tail reg.
 3. The original tail reg located at bar23, the above bar45 tail reg
    could provide better bandwidth from the hardware perspective.

The hns3 driver only support direct write tail reg (also have the name
of quick doorbell), the detail:
Considering compatibility, firmware will report Tx push capa if the
hardware support it.

Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
Signed-off-by: Min Hu (Connor) <humin29@huawei.com>