target-arm: A64: Add SIMD simple 64 bit insns from scalar 2-reg misc Implement the simple 64 bit integer operations from the SIMD scalar 2-register misc group (C3.6.12): the comparisons against zero, plus ABS and NEG. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <rth@twiddle.net>