RDMA/hns: fix build regression

RDMA/hns: fix build regression

The 0day build system flags implicit includes as errors.  A patch from
Matan Barak to allow hns_roce, an aarch64 specific RDMA driver, to be
built on other arches, but it resulted in build regressions.  The
problem is that hns_roce_device.h needs a definition for __raw_writeq
but did not have an include to provide it.  Add <linux/io.h> as an
include to resolve the issue.

Signed-off-by: Doug Ledford <dledford@redhat.com>