mlxsw: spectrum_router: Prevent ipv6 gateway with v4 route via replace and append

mlxsw currently does not support v6 gateways with v4 routes. Commit
19a9d136 ("ipv4: Flag fib_info with a fib_nh using IPv6 gateway")
prevents a route from being added, but nothing stops the replace or
append. Add a catch for them too.
    $ ip  ro add 172.16.2.0/24 via 10.99.1.2
    $ ip  ro replace 172.16.2.0/24 via inet6 fe80::202:ff:fe00:b dev swp1s0
    Error: mlxsw_spectrum: IPv6 gateway with IPv4 route is not supported.
    $ ip  ro append 172.16.2.0/24 via inet6 fe80::202:ff:fe00:b dev swp1s0
    Error: mlxsw_spectrum: IPv6 gateway with IPv4 route is not supported.
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c

@@ -6105,6 +6105,8 @@ static int mlxsw_sp_router_fib_event(struct notifier_block *nb,
 			return notifier_from_errno(err);
 		break;
 	case FIB_EVENT_ENTRY_ADD:
+	case FIB_EVENT_ENTRY_REPLACE: /* fall through */
+	case FIB_EVENT_ENTRY_APPEND:  /* fall through */
 		if (router->aborted) {
 			NL_SET_ERR_MSG_MOD(info->extack, "FIB offload was aborted. Not configuring route");
 			return notifier_from_errno(-EINVAL);