IB/hns: Explicitly include linux/of.h

hns_roce_hw_v1.c uses DT interfaces but relies on implict inclusion of
linux/of.h which means that changes in other headers could break the
build, as happened in -next for arm64 today.  Add an explicit include.
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hns/hns_roce_hw_v1.c

@@ -33,6 +33,7 @@
 #include <linux/platform_device.h>
 #include <linux/acpi.h>
 #include <linux/etherdevice.h>
+#include <linux/of.h>
 #include <rdma/ib_umem.h>
 #include "hns_roce_common.h"
 #include "hns_roce_device.h"