target/arm: Simplify iteration over bit widths

target/arm: Simplify iteration over bit widths

Order suf[] by the log8 of the width.
Use ARRAY_SIZE instead of hard-coding 128.

This changes the order of the union definitions,
but retains the order of the union-of-union members.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230227213329.793795-10-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>