fm10k: add call to fm10k_clean_all_rx_rings in fm10k_down

This prevents a memory leak in fm10k_set_ringparams. The leak occurs
because we go down, change ring parameters, and then come up. However,
fm10k_down on its own is not clearing the Rx rings. Since fm10k_up
assumes the rings are clean we basically drop the buffers and leak a
bunch of memory. Eventually we hit dirty page faults and reboot the
system. This issue does not occur elsewhere because other flows that
involve fm10k_down go through fm10k_close which immediately called
fm10k_free_all_rx_resources which properly cleans the rings.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>