edac: i5400 fix csrow mapping

The i5400 EDAC driver has several bugs with chip-select row computation
which most likely lead to bugs in detailed error reporting.  Attempts to
contact the authors have gone mostly unanswered so I am presenting my diff
here.  I do not subscribe to lkml and would appreciate being kept in the
cc.

The most egregious problem was miscalculating the addresses of MTR
registers after register 0 by assuming they are 32bit rather than 16.
This caused the driver to miss half of the memories.  Most motherboards
tend to have only 8 dimm slots and not 16, so this may not have been
noticed before.

Further, the row calculations multiplied the number of dimms several
times, ultimately ending up with a maximum row of 32.  The chipset only
supports 4 dimms in each of 4 channels, so csrow could not be higher than
4 unless you use a row per-rank with dual-rank dimms.  I opted to
eliminate this behavior as it is confusing to the user and the error
reporting works by slot and not rank.  This gives a much clearer view of
memory by slot and channel in /sys.

Signed-off-by: Jeff Roberson <jroberson@jroberson.net>
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>