MAINTAINERS: microblaze: use LKML as mailing list

MAINTAINERS: microblaze: use LKML as mailing list

microblaze-uclinux mailing list is almost dead and it is just causing
troubles for non subscribers which are getting email about waiting for
moderator.  Approval never happens.  Move it to LKML.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reported-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>