x86, ucode-amd: Ensure ucode update on suspend/resume after CPU off/online cycle

When switching a CPU offline/online and then doing
suspend/resume, ucode is not updated on this CPU.

This is due to the microcode_fini_cpu() call which frees uci->mc
when setting the CPU offline:

  static void microcode_fini_cpu_amd(int cpu)
  {
          struct ucode_cpu_info *uci = ucode_cpu_info + cpu;

          vfree(uci->mc);
          uci->mc = NULL;
  }

When the CPU is set online uci->mc is still NULL because no
ucode update is required.

Finally this prevents ucode update when resuming after suspend:

  static enum ucode_state microcode_resume_cpu(int cpu)
  {
        struct ucode_cpu_info *uci = ucode_cpu_info + cpu;

        if (!uci->mc)
                return UCODE_NFOUND;

        ...
  }

Fix is to check whether uci->mc is valid before
microcode_resume_cpu() is called.

Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: dimm <dmitry.adamushko@gmail.com>
LKML-Reference: <20091111190329.GF18592@alberich.amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>