drivers/edac: add edac_device class

This patch adds the new 'class' of object to be managed, named: 'edac_device'.

As a peer of the 'edac_mc' class of object, it provides a non-memory centric
view of an ERROR DETECTING device in hardware. It provides a sysfs interface
and an abstraction for varioius EDAC type devices.

Multiple 'instances' within the class are possible, with each 'instance'
able to have multiple 'blocks', and each 'block' having 'attributes'.

At the 'block' level there are the 'ce_count' and 'ue_count' fields
which the device driver can update and/or call edac_device_handle_XX()
functions. At each higher level are additional 'total' count fields,
which are a summation of counts below that level.

This 'edac_device' has been used to capture and present ECC errors
which are found in a a L1 and L2 system on a per CORE/CPU basis.

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>