[CLAP] Fix logit scales dtype for fp16

[sanchit-gandhi]

What does this PR do?

On some hardware, taking torch.log of a tensor in float16 on the CPU fails:

in __init__(self, config)
   1956         audio_config = config.audio_config
   1957 
-> 1958         self.logit_scale_a = nn.Parameter(torch.log(torch.tensor(config.logit_scale_init_value)))
   1959         self.logit_scale_t = nn.Parameter(torch.log(torch.tensor(config.logit_scale_init_value)))
   1960 

RuntimeError: "log_vml_cpu" not implemented for 'Half'

Note that this only failed for me on a Colab T4, but not on a Titan RTX (used to test #25682).

Let's take math.log then convert it to a tensor - this will respect the dtype of the model but not take torch.log of a float16 CPU param.

[HuggingFaceDocBuilderDev]

The documentation is not available anymore as the PR was closed or merged.

[ArthurZucker]

On CPU you can't use half anyway no?

[sanchit-gandhi]

Yep try with this:

import torch

torch.tensor(0).half().dtype()

Gives:

tensor(0., dtype=torch.float16)

Is used when we load diffusers pipelines in fp16 (load state dict in fp16 on cpu then move to cuda)