The NIC driver should only enable interrupts when napi_complete_done()
returns true. This patch adds the check for ixgbe.

Cc: stable@vger.kernel.org # 4.10+
Suggested-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NSong Liu <songliubraving@fb.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>