target/arm: Support FPCR.AH in SME FMOPS, BFMOPS

target/arm: Support FPCR.AH in SME FMOPS, BFMOPS

For non-widening, we can use float_muladd_negate_product,
For widening, which uses dot-product, we need to handle
the negation explicitly.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250704142112.1018902-104-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>