tcg: Make call address a constant parameter

tcg: Make call address a constant parameter

Avoid allocating a tcg temporary to hold the constant address,
and instead place it directly into the op_call arguments.

At the same time, convert to the newly introduced tcg_out_call
backend function, rather than invoking tcg_out_op for the call.

Signed-off-by: Richard Henderson <rth@twiddle.net>