x86/mce: Move MCACOD defines from mce-severity.c to <asm/mce.h>

We will need some of these values in mce.c. Move them to the
appropriate header file so they are available.

Acked-by: Borislav Petkov <bp@amd64.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Cc: Chen Gong <gong.chen@linux.intel.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Link: http://lkml.kernel.org/r/0ccfb1af5fe35e537b7cd8e4d448bf7d851dbfb9.1343078495.git.tony.luck@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>