x86: mce: Remove old i386 machine check code

As announced in feature-remove-schedule.txt remove CONFIG_X86_OLD_MCE

This patch only removes code.

The ancient machine check code for very old systems that are not supported
by CONFIG_X86_NEW_MCE is still kept.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>