Revert "percpu: implement generic percpu refcounting 3"

This reverts commit 2817d11b02c74ad3bc8914923fe4ba5a4c0b0008.
Revert "percpu: implement generic percpu refcounting 2"

This reverts commit e20d20ee84b830679070cbdc71389e36486c7309.
Revert "percpu: implement generic percpu refcounting 1"

This reverts commit 005eeacc721c70c942565e2f8073d4c59214d81c.