l2cap: Use CHECK for memory allocation errors

                                  L2CAP_FIXED_CHNL_SMP_BIT;

  l2cb.rcv_pending_q = list_new(NULL);

  if (l2cb.rcv_pending_q == NULL)

    LOG_ERROR(LOG_TAG,

              "%s unable to allocate memory for link layer control block",

              __func__);

  CHECK(l2cb.rcv_pending_q != NULL);

  l2cb.receive_hold_timer = alarm_new("l2c.receive_hold_timer");

}