- Use `6x86MX' instead of `M2'. Cyrix officially use `6x86MX' for the

- Use `6x86MX' instead of `M2'.  Cyrix officially use `6x86MX' for the
  CPU code-named `M2'.

- Use the result of cpuid instruction instead of DIR to identify
  6x86MX cpu.  DIR0 and DIR1 are not documented in the data sheet, and
  cpuid instruction is enabled at reset time.

- Add a function, init_6x86MX() to initialize 6x86MX cpu.  It supports
  CPU_SUSP_HLT and CPU_IORT options.  It always sets NC1 (640K - 1M is
  not cached.), and enables L1 cache in write-back mode.

- Fix typo in the comment in identblue().