edac: i5100 fix initialization code

Allow csrows to properly initialize when the topology only has active
channels on 2 and 3.  This new check allows proper detection and
initialization in this topology.  Only checking the first mrt that
represented channels 0 and 1 is not sufficient.

I also fixed up the related debug information path.  I can submit as a 2nd
patch if needed.

Signed-off-by: Keith Mannthey <kmannth@us.ibm.com>
Acked-by: Aristeu Rozanski <aris@ruivo.org>
Signed-off-by: Doug Thompson <dougthompson@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>