RDMA/hns: Get rid of page operation after dma_alloc_coherent

RDMA/hns: Get rid of page operation after dma_alloc_coherent

In general, dma_alloc_coherent() returns a CPU virtual address and
a DMA address, and we have no guarantee that the underlying memory
even has an associated struct page at all.

This patch gets rid of the page operation after dma_alloc_coherent,
and records the VA returned form dma_alloc_coherent in the struct
of hem in hns RoCE driver.

Fixes: 9a44353("IB/hns: Add driver files for hns RoCE driver")
Signed-off-by: Wei Hu (Xavier) <[email protected]>
Signed-off-by: Shaobo Xu <[email protected]>
Signed-off-by: Lijun Ou <[email protected]>
Signed-off-by: Yixian Liu <[email protected]>
Signed-off-by: Xiping Zhang (Francis) <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>