target/hppa: Set FloatInfZeroNaNRule explicitly

target/hppa: Set FloatInfZeroNaNRule explicitly

Set the FloatInfZeroNaNRule explicitly for the HPPA target,
so we can remove the ifdef from pickNaNMulAdd().

As this is the last target to be converted to explicitly setting
the rule, we can remove the fallback code in pickNaNMulAdd()
entirely.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20241202131347.498124-14-peter.maydell@linaro.org