### What this PR does / why we need it?
Only CPU tensors with `pin_memory=True` can be asynchronously copied to
the device. Currently, there are two instances where non-pinned CPU
tensors are being copied to the device, which will trigger synchronous
operations, reducing the expected benefits of asynchronous scheduling.
- vLLM version: v0.11.0
- vLLM main:
83f478bb19
Signed-off-by: realliujiaxu <realliujiaxu@163.com>