Replace hardcoded 0 with macro PERF_COUNT_CORE_CLK
Replace hardcoded 0 with macro PERF_COUNT_CORE_CLK

... to make it more independent of constant values.

Signed-off-by: Ravi Bangoria <c3c2a342b6d0b20c2fffcb500dabb9f78ad28a56@linux.vnet.ibm.com>

01org/numatop,intel/numatop,01org/numatop,ColinIanKing/numatop,intel/numatop,ColinIanKing/numatop,ColinIanKing/numatop