target/arm: Implement fp16 for Neon VRINTX

Convert the Neon VRINTX insn to use gvec, and use this to implement
fp16 support for it.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200828183354.27913-42-peter.maydell@linaro.org
3 files changed