i40e: let go of the past

If we reset a VF, its VSI goes away, and it gets a new one. So don't
hang on to the now-stale local VSI pointer. It just leads to suffering
and kernel panics.

Change-ID: Ia8823b4e85893e95e963acee284968022b29177a
Signed-off-by: NMitch Williams <mitch.a.williams@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c

@@ -2203,6 +2203,8 @@ int i40e_ndo_set_vf_port_vlan(struct net_device *netdev,
 		 * and then reloading the VF driver.
 		 */
 		i40e_vc_disable_vf(pf, vf);
+		/* During reset the VF got a new VSI, so refresh the pointer. */
+		vsi = pf->vsi[vf->lan_vsi_idx];
 	}
 
 	/* Check for condition where there was already a port VLAN ID