RDMA/hns: Prevent le32 from being implicitly converted to u32

Replace BUILD_BUG_ON_ZERO() with BUILD_BUG_ON() to avoid sparse
complaining "restricted __le32 degrades to integer".

Link: https://lore.kernel.org/r/1617354454-47840-10-git-send-email-liweihang@huawei.com


Signed-off-by: Lang Cheng <chenglang@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>