isisd: fix update link params after circuit is up

isisd: fix update link params after circuit is up

If the link-params are set when the circuit not yet up, the link-params
are never updated.

isis_link_params_update() is called from isis_circuit_up() but returns
immediately because circuit->state != C_STATE_UP. circuit->state is
updated in isis_csm_state_change after isis_circuit_up().

> struct isis_circuit *isis_csm_state_change(enum isis_circuit_event event,
> 					   struct isis_circuit *circuit,
> 					   void *arg)
> {
> [...]
> 			if (isis_circuit_up(circuit) != ISIS_OK) {
> 				isis_circuit_deconfigure(circuit, area);
> 				break;
> 			}
> 			circuit->state = C_STATE_UP;
> 			isis_event_circuit_state_change(circuit, circuit->area,
> 							1);

Do not return isis_link_params_update() if circuit->state != C_STATE_UP.

Fixes: 0fdd8b2b11 ("isisd: update link params after circuit is up")
Signed-off-by: Louis Scalbert <louis.scalbert@6wind.com>