acpu: export krait variant to debugfs

Signed-off-by: Dennis Rassmann <showp1984@gmail.com>
acpu: krait_variant: add detection for unknown pvs

Signed-off-by: Dennis Rassmann <showp1984@gmail.com>
acpu: fix krait variant export
This was a classic example for a clean cherry pick, but broken code.

Signed-off-by: Dennis Rassmann <showp1984@gmail.com>
acpu: show a useful warn message

Signed-off-by: Dennis Rassmann <showp1984@gmail.com>