tcg/arm: Rationalize args to tcg_out_qemu_{ld,st}

tcg/arm: Rationalize args to tcg_out_qemu_{ld,st}

Interpret the variable argument placement in the caller.
Pass data_type instead of is_64.  We need to set this in
TCGLabelQemuLdst, so plumb this all the way through from tcg_out_op.

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