mark arm.arm (v4/v5) kernels as NO_UNIVERSE for now

r354290 removed arm.arm from universe, but arm.arm kernels were still
found and built during the kernel stage. I'm not aware of a better way
to address this at the moment, but since there aren't many arm.arm
kernels anyhow just add an explicit NO_UNIVERSE to them.

Reported by: rpokala