[CPUFREQ] Make acpi-cpufreq more robust against BIOS freq changes behind our back.

We checked the hardware freq with OS cached freq value in get_cur_freqon_cpu().

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Dave Jones <davej@redhat.com>