switchdev: fix return value of switchdev_port_fdb_dump in case of error
switchdev_port_fdb_dump is used as .ndo_fdb_dump. Its return value is
idx, so we cannot return errval.
Fixes: 173a4d6ba8b8 ("switchdev: add support for fdb add/del/dump via switchdev_port_obj ops.") Signed-off-by: Jiri Pirko <jiri@mellanox.com> Acked-by: Sridhar Samudrala <sridhar.samudrala@intel.com> Acked-by: Scott Feldman<sfeldma@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>