x86, mce: rename _64.c files which are no longer 64-bit-specific

Rename files that are no longer 64bit specific:
	mce_amd_64.c	=> mce_amd.c
	mce_intel_64.c	=> mce_intel.c

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>