Bug: randn_tensor MPS info-log suppression never triggers (compares torch.device to string)

[Ricardo-M-L]

Describe the bug

In src/diffusers/utils/torch_utils.py, randn_tensor suppresses the CPU-generator info log on MPS with:

if device != "mps":
    logger.info(...)

device is a torch.device object, so the comparison to the string "mps" is always True - the log fires even on MPS targets where it's meant to be suppressed. This has been silently broken since the check was introduced in #1902.

Reproduction

import torch
from diffusers.utils import torch_utils

gen = torch.Generator(device="cpu")
torch_utils.randn_tensor((1, 2), generator=gen, device=torch.device("mps"), dtype=torch.float32)
# -> info log "The passed generator was created on 'cpu'..." still prints

Expected behavior

Compare device.type != "mps" instead. Fix + regression test in PR #14501 (rebase of approved-but-unmerged #13508).