drivers/edac: add device sysfs attributes

Added new controls for the edac_device and edac_mc sysfs folder.
These can be initialized by the low level driver to provide misc
controls into the low level driver for its use

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>