[fix] refer use_framewise_encoding on AutoencoderKLHunyuanVideo._encode

[hanchchch]

What does this PR do?

AutoencoderKLHunyuanVideo._encode is currently refering to use_framewise_decoding, instead of use_framewise_encoding. Fixed it to use_framewise_encoding

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[a-r-r-o-w]

Thanks for the fix!

[hanchchch]

have no idea why the test is failing lol