[POWERPC] Use menuconfig objects II - Macintosh

Make a "menuconfig" out of the Kconfig objects "menu, ..., endmenu",
so that the user can disable all the options in that menu at once
instead of having to disable each option separately.

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>