x86, cpu: Convert FDIV bug detection

... to the new facility. Add a reference to the wikipedia article
explaining the FDIV test we're doing here.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1363788448-31325-4-git-send-email-bp@alien8.de


Signed-off-by: H. Peter Anvin <hpa@zytor.com>