target/hexagon: Set default NaN pattern explicitly

target/hexagon: Set default NaN pattern explicitly

Set the default NaN pattern explicitly for hexagon.
Remove the ifdef from parts64_default_nan(); the only
remaining unconverted targets all use the default case.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20241202131347.498124-52-peter.maydell@linaro.org