drivers/edac: i5000 define typo

Found a typo in one of the #defines in the driver

MTR_DIM_RANKS --> MTR_DIMM_RANK

Signed-off-by: Marisuz Kozlowski <m.kozlowski@tuxland.pl>
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>