Otherwise we end up with $NARCH copies of that Kconfig, each slightly
different. The top-level entry can be made to depend on the archs that
actually have some virt capability, so as not to show empty an menu.
I dislike the duplication, too, but
1) it's a CPU capability, and that's where it belongs in the menu.
2) And as you can see from the difference between the x86_64 and i386
help text, there are real platform differences (and not mentioning
what's under the menu would be kinda cheating).
3) Virtualization doesn't even make sense as an option for some
platforms where it's always on.