drivers/edac: remove null from statics

Patches to conform to coding style, namely static don't need to be initialized
to NULL nor '0', as that is the default

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>