ice: Fix couple of issues in ice_vsi_release

Currently the driver is calling ice_napi_del() and then
unregister_netdev(). The call to unregister_netdev() will result in a
call to ice_stop() and then ice_vsi_close(). This is where we call
napi_disable() for all the MSI-X vectors. This flow is reversed so make
the changes to ensure napi_disable() happens prior to napi_del().

Before calling napi_del() and free_netdev() make sure
unregister_netdev() was called. This is done by making sure the
__ICE_DOWN bit is set in the vsi->state for the interested VSI.

Signed-off-by: Brett Creeley <brett.creeley@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>