Nexus segfault when there are offline CPUs

I got a segfault when running the `create_session_test` at the following line:
https://github.com/erpc-io/eRPC/blob/dff45896f7bb6bf43f38a8d7a7034c6ff79791f7/src/nexus_impl/nexus.cc#L63

The problem is that `sm_thread_lcore_index` is assigned to be the last lcore at line 61 without considering its status while `get_lcores_for_numa_node` returns only online lcores.