Bugfix wrong use of qsort

- The qsort() function is defined as:
  void qsort(void *base, size_t nmemb, size_t size,
    int (*compar)(const void *, const void *));
  and sorts an array with nmemb elements of size size.
- in the gNB scheduling functions, nmemb and size were swapped
- this was causing a stack overflow ending with a SEGFAULT under certain circumstances