target/arm: Pass ZA to helper_sve2_fmlal_zz[zx]w_s

target/arm: Pass ZA to helper_sve2_fmlal_zz[zx]w_s

Indicate whether to use FPST_FPCR or FPST_ZA via bit 2 of
simd_data(desc).  For SVE, this bit remains zero.
For do_FMLAL_zzzw, this requires no change.
For do_FMLAL_zzxw, move the index up one bit.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250704142112.1018902-35-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>