target/microblaze: Explicitly set 2-NaN propagation rule

target/microblaze: Explicitly set 2-NaN propagation rule

Set the NaN propagation rule explicitly for the float_status word
used in the microblaze target.

This is probably not the architecturally correct behaviour,
but since this is a no-behaviour-change patch, we leave a
TODO note to that effect.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20241025141254.2141506-19-peter.maydell@linaro.org