fixed bug in defining embed dim for UNet1D (#12111)
* fixed bug in defining embed dim
* matched 1d temb process to 2d
* Update src/diffusers/models/unets/unet_1d.py
Co-authored-by: Dhruv Nair <dhruv.nair@gmail.com>
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Co-authored-by: Dhruv Nair <dhruv.nair@gmail.com>
