Review `time_resolution_init()`

Function `time_resolution_init()` located in file `main/main.c` estimates the frequency of the TSC register and sets its result in a couple global variable in different units (e.g. `cycles_per_sec`). DPDK has function `rte_get_tsc_hz()`, which is equivalent to the global variable `cycles_per_sec`.

Which function is more precise, `time_resolution_init()` or `rte_get_tsc_hz()`? If `time_resolution_init()`, we should submit a patch to DPDK. In any case, we should adopt `rte_get_tsc_hz()` in `time_resolution_init()` to simplify our code.

We should also investigate if the global variables are still needed. For example, should we replace variable `cycles_per_sec` with `rte_get_tsc_hz()` or keep it?