i40iw: Use correct src address in memcpy to rdma stats counters

hw_stats is a pointer to i40_iw_dev_stats struct in i40iw_get_hw_stats().
Use hw_stats and not &hw_stats in the memcpy to copy the i40iw device stats
data into rdma_hw_stats counters.

Fixes: b40f4757 ("IB/core: Make device counter infrastructure dynamic")

Cc: stable@vger.kernel.org # 4.7+
Signed-off-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Faisal Latif <faisal.latif@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>