This patch adds null dev check for the 'cfg->rc_via_table ==
NEIGH_LINK_TABLE or dev_get_by_index() failed' case
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NRoopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>