No more users of this keyword. Drop it according to the notice by
commit 6341e62b212a ("kconfig: use bool instead of boolean for type
definition attributes").
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Luis R. Rodriguez <mcgrof@kernel.org> Signed-off-by: Christian Lamparter <chunkeey@gmail.com>