RDMA/hns: Refactor post recv flow

mainline inclusion
from mainline-v5.12-rc1
commit 9ae2a37e
category: bugfix
bugzilla: 174002
CVE:NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9ae2a37e6ae650d7d81f4afede9d879937cab5db

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Refactor post recv flow by removing unnecessary checking and removing
duplicated code.

Link: https://lore.kernel.org/r/1611997090-48820-10-git-send-email-liweihang@huawei.com


Signed-off-by: Xi Wang <wangxi11@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: wangsirong <wangsirong@huawei.com>
Reviewed-by: ChunZhi Hu <huchunzhi@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>