x86, mce: Check the result of ancient_init()

x86, mce: Check the result of ancient_init()

Because "ancient CPUs" like p5 and winchip don't have X86_FEATURE_MCA
(I suppose so), mcheck_cpu_init() on such CPUs will return at check of
mce_available() after __mcheck_cpu_ancient_init().

It is hard to know this implicit behavior without knowing the CPUs
well. So make it clear that we leave mcheck_cpu_init() when the CPU is
initialized in __mcheck_cpu_ancient_init().

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/4DEED74B.20502@jp.fujitsu.com
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>