insane: Clean up horrible return value processing code

insane: Clean up horrible return value processing code

Whilst in theory return values are nice, handling the complex
aggregation of the return values is ugly. The code already uses QA_SANE
as a marker to signal problems. Whilst that isn't as idealistic, it
makes the code massively cleaner, so rely on this instead.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>