softfloat: rename *IsNaN variables to *IsQuietNaN Similarly to what has been done in commit 185698715dfb18c82ad2a5dbc169908602d43e81 rename the misnamed *IsNaN variables into *IsQuietNaN. Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>