x86: mce: Remove the frozen cases in the hotplug code

No point in having double cases if we can simply mask the FROZEN bit
out.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chen Gong <gong.chen@linux.intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>