target/arm: Avoid tcg_const_ptr in disas_simd_zip_trn

target/arm: Avoid tcg_const_ptr in disas_simd_zip_trn

It is easy enough to use mov instead of or-with-zero and relying
on the optimizer to fold away the or.  Use an array for the output,
rather than separate tcg_res{l,h} variables.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>