X86_HT is used for hyperthreading or multicore on 32-bit.
The X86_HT on 64-bit is different from 32-bit, it means hyperthreading only.
And X86_HT is not used on 64-bit except from cpu/initel_cacheinfo.c.
Unify X86_HT for hyperthreading or multicore.
Turn X86_HT on when X86_64 and SMP are enabled.