target/ppc: Use env->fp_status in helper_compute_fprf functions

target/ppc: Use env->fp_status in helper_compute_fprf functions

In the helper_compute_fprf functions, we pass a dummy float_status
in to the is_signaling_nan() function. This is unnecessary, because
we have convenient access to the CPU env pointer here and that
is already set up with the correct values for the snan_bit_is_one
and no_signaling_nans config settings. is_signaling_nan() doesn't
ever update the fp_status with any exception flags, so there is
no reason not to use env->fp_status here.

Use env->fp_status instead of the dummy fp_status.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20241202131347.498124-34-peter.maydell@linaro.org