### What this PR does / why we need it? The former PR https://github.com/vllm-project/vllm-ascend/pull/736 select the valid token inside the `input_ids` and `position_ids` breaks the necessary padding required by torchair. In this PR, we pending the pad logic after the multimodal part. Signed-off-by: ganyi <pleaplusone.gy@gmail.com>