BKL is not needed for anything in mce_open because it has
an own spinlock. Remove it.

[ Impact: cleanup ]
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>