MAINTAINERS: Change mailing list info for CRIS

Posting to the dev-etrax mailing list is only allowed for subscribers,
and the list is more geared toward user applications than kernel
developers.

Change to newly created mailing list for CRIS.

Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>