drivers/edac: mod use edac_core.h

In the refactoring of edac_mc.c into several subsystem files,
the header file edac_mc.h became meaningless. A new header file
edac_core.h was created. All the files that previously included
"edac_mc.h" are changed to include "edac_core.h".

Signed-off-by: Douglas Thompson <dougthompson@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>