net: hns3: Remove io_stop_wc() calls after __iowrite64_copy()

Now that the ARM64 arch implementation does the DGH as part of
__iowrite64_copy() there is no reason to open code this in drivers.

Link: https://lore.kernel.org/r/5-v3-1893cd8b9369+1925-mlx5_arm_wc_jgg@nvidia.com


Reviewed-by: Jijie <Shao&lt;shaojijie@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>