RDMA/hns: Solve the overflow of the calc_pg_sz()

calc_pg_sz() may gets a data calculation overflow if the PAGE_SIZE is 64 KB
and hop_num is 2. It is because that all variables involved in calculation
are defined in type of int. So change the type of bt_chunk_size,
buf_chunk_size and obj_per_chunk_default to u64.

Fixes: ba6bb7e9

 ("RDMA/hns: Add interfaces to get pf capabilities from firmware")
Link: https://lore.kernel.org/r/1600509802-44382-6-git-send-email-liweihang@huawei.com
Signed-off-by: Jiaran Zhang <zhangjiaran@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>