Discourage the use of keyword 'boolean' for type definition attributes of
config options as support for it will be dropped later on.

See http://lkml.kernel.org/r/cover.1418003065.git.cj@linux.comSigned-off-by: Christoph Jaeger <cj@linux.com>
Suggested-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Joe Perches <joe@perches.com>
Acked-by: Paul Bolle <pebolle@tiscali.nl>
Tested-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>