[ROCm][BugFix]Fix get_cu_count in rocm_aiter_fa.py (#28618)

Signed-off-by: ganyi <ygan@amd.com>

Author: ganyi1996ppo

vllm/v1/attention/backends/rocm_aiter_fa.py

@@ -18,6 +18,7 @@
 from vllm.logger import init_logger
 from vllm.platforms import current_platform
 from vllm.utils.math_utils import cdiv
+from vllm.utils.platform_utils import get_cu_count
 from vllm.v1.attention.backends.utils import (
     AttentionCGSupport,
     AttentionMetadataBuilder,
@@ -38,7 +39,7 @@ def block_size(x, head_dim):
         return min(65536 // x.element_size(), triton.next_power_of_2(head_dim))
 
     def num_programs(total_tokens):
-        return min(total_tokens, current_platform.get_cu_count())
+        return min(total_tokens, get_cu_count())
 
     @triton.jit
     def cp_mha_gather_cache_kernel(