IA32-Intel Devel guide Volume 3A - 14.3.2.1
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Opportunistic processor performance operation can be disabled by setting bit 38 of
IA32_MISC_ENABLES. This mechanism is intended for BIOS only. If
IA32_MISC_ENABLES[38] is set, CPUID.06H:EAX[1] will return 0.

Better detect things via cpuid, this cleans up the code a bit
and the MSR parts were not working correctly anyway.
Signed-off-by: Thomas Renninger <trenn@suse.de>
CC: lenb@kernel.org
CC: linux@dominikbrodowski.net
CC: cpufreq@vger.kernel.org
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>