RDMA/hns: Remove redundant 'use_lowmem' argument from hns_roce_init_hem_table()

As hns_roce_init_hem_table() is always called with use_lowmem
being '1', and table->lowmem is set according to that argument,
so remove table->lowmem too.

Also, as the table->lowmem is used to indicate a dma buffer
is allocated with GFP_HIGHUSER or GFP_KERNEL, and calling
dma_alloc_coherent() with GFP_KERNEL seems like a common
pattern.

Link: https://lore.kernel.org/r/20220922123315.3732205-7-xuhaoyue1@hisilicon.com


Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Haoyue Xu <xuhaoyue1@hisilicon.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>