Fix autoencoder_kl_wan.py bugs for Wan2.2 VAE (#12335)
* Update autoencoder_kl_wan.py
When using the Wan2.2 VAE, the spatial compression ratio calculated here is incorrect. It should be 16 instead of 8. Pass it in directly via the config to ensure it’s correct here.
* Update autoencoder_kl_wan.py
