RDMA/hns: Support flexible wqe buffer page size

driver inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I87LTM



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Currently, driver fixedly allocates 4K pages for user space WQE buffer
even in a 64K system. This results in HW reading WQE with a granularity
of 4K even in a 64K system. Considering that we support 1024-byte inline,
in the scenario of using SQ inline, HW will switch pages every 4 WQEs.
This will introduce a delay of about 400ns, which is an average delay of
100ns per packet.

In order to improve performance, we allow user-mode driver to use more
flexible WQE buffer page size allocation strategies, which allowing
user-mode driver to configure WQE buffer using pages between 4K to
system PAGESIZE.

This feature needs to be used in conjunction with the user-mode driver.
In order to ensure forward compatibility, if the user-mode driver does
not support this feature, the kernel mode will continue to use a fixed
4K pagesize.

Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>