MAINTAINERS: update EDAC information

The bluesmoke mailing list no longer works, so use
linux-edac@vger.kernel.org.  And, use a less restrictive pattern so all
drivers/edac changes go to linux-edac as well.

Borislav suggested I just push this through the tile tree since there
is currently no core edac maintainer (emails to Doug Thompson bounce).

Acked-by: Borislav Petkov <bp@amd64.org>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>