Turbostat: use MSR_IA32_TSC instead of rdtsc
Turbostat: Only open msr once in get_counters
Turbostat set_temperature_target: get msr from the correct cpu
Turbostat: Refactor migrate CPU before get_MSR

In two out of three "get_msr" calls, there is a CPU migration, which
does not seem to be used by something else (in one case, it was used by
the rdtsc call).
Move the migrate call directly into the open_msr function
Turbostat: better error handling for get/read_msr
Turbostat: use sizeof for the buffer sier of s*printf
Turbostat: use ssnprintf instead of snprintf