x86: initial integration of cpuid utility

cpuid, a simple CPUID decoder/dumper for x86/x86_64
https://github.com/tycho/cpuid

The version integrated is directly a clone of commit fe59bcd, and put
into arch/x86/lib/cpuid/ in the U-Boot source tree.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>