RDMA/hns: Fix PBL page MTR find

driver inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5Y79T



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Now, The address of the first two pages in the MR will be searched.
And an exception will occur when there is only one page in this MR.

This patch fix the number of page to search.

Fixes: 9b2cf76c ("RDMA/hns: Optimize PBL buffer allocation process")
Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
Reviewed-by: Yangyang Li <liyangyang20@huawei.com>
Reviewed-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>