x86, AMD: Disable wrongly set X86_FEATURE_LAHF_LM CPUID bit

fbd8b1819e80ac5a176d085fdddc3a34d1499318 turns off the bit for
/proc/cpuinfo. However, a proper/full fix would be to additionally
turn off the bit in the CPUID output so that future callers get
correct CPU features info.

Do that by basically reversing what the BIOS wrongfully does at boot.

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
LKML-Reference: <1251705011-18636-3-git-send-email-petkovbb@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>