[Minor][Spec Decode] Remove compiled_softmax (#15416)

Signed-off-by: Woosuk Kwon <woosuk.kwon@berkeley.edu>

vllm/v1/sample/rejection_sampler.py

@@ -9,7 +9,6 @@ import triton.language as tl
 from vllm.logger import init_logger
 from vllm.v1.sample.metadata import SamplingMetadata
 from vllm.v1.sample.ops.topk_topp_sampler import apply_top_k_top_p
-from vllm.v1.sample.ops.utils import compiled_softmax
 from vllm.v1.spec_decode.metadata import SpecDecodeMetadata
 
 logger = init_logger(__name__)
@@ -275,8 +274,7 @@ def compute_probs(
     # NOTE(woosuk): `apply_top_k_top_p` uses sorting to calculate the mask,
     # which is slow for large vocab sizes. This may cause performance issues.
     logits = apply_top_k_top_p(logits, top_k, top_p)
-
-    output_prob = compiled_softmax(logits)
+    output_prob = logits.softmax(dim=-1, dtype=torch.float32)
     return output_prob