RDMA/hns: Delete redundant assignment values

driver inclusion
category: cleanup
bugzilla: https://gitee.com/openeuler/kernel/issues/I6GT7F



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The variables "hop_num" and "unit" are assigned values twice in
get_best_hop_num(), which affects code maintainability. Therefore,
redundant values are deleted.

Fixes: cf2f2029 ("RDMA/hns: Support adaptive hopnum for MTR")
Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>