[Misc] Use deprecated for seed_everything (#31780)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

benchmarks/kernels/benchmark_reshape_and_cache_flash.py

@@ -11,11 +11,11 @@ from vllm.attention.ops.triton_reshape_and_cache_flash import (
     triton_reshape_and_cache_flash,
 )
 from vllm.logger import init_logger
-from vllm.platforms import current_platform
 from vllm.utils.argparse_utils import FlexibleArgumentParser
 from vllm.utils.torch_utils import (
     STR_DTYPE_TO_TORCH_DTYPE,
     create_kv_caches_with_random_flash,
+    set_random_seed,
 )
 
 logger = init_logger(__name__)
@@ -49,7 +49,7 @@ def run_benchmark(
     if implementation == "triton" and kv_cache_layout == "HND":
         return float("nan")  # Triton does not support HND layout yet.
 
-    current_platform.seed_everything(42)
+    set_random_seed(42)
     torch.set_default_device(device)
 
     # create random key / value tensors [T, H, D].