target/arm: Remove redundant advsimd float16 helpers

target/arm: Remove redundant advsimd float16 helpers

The advsimd_addh etc helpers defined in helper-a64.c are identical to
the vfp_addh etc helpers defined in helper-vfp.c: both take two
float16 inputs (in a uint32_t type) plus a float_status* and are
simple wrappers around the softfloat float16_* functions.

(The duplication seems to be a historical accident: we added the
advsimd helpers in 2018 as part of the A64 implementation, and at
that time there was no f16 emulation in A32.  Then later we added the
A32 f16 handling by extending the existing VFP helper macros to
generate f16 versions as well as f32 and f64, and didn't realise we
could clean things up.)

Remove the now-unnecessary advsimd helpers and make the places that
generated calls to them use the vfp helpers instead. Many of the
helper functions were already unused.

(The remaining advsimd_ helpers are those which don't have vfp
versions.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-26-peter.maydell@linaro.org