[CI] Fix broken compile tests due to unsupported SiluMul+Nvfp4Quant fusion (#23973)

Signed-off-by: Yong Hoon Shin <yhshin@meta.com>
Co-authored-by: Roger Wang <hey@rogerw.io>

vllm/compilation/activation_quant_fusion.py

@@ -29,8 +29,9 @@ SILU_MUL_OP = torch.ops._C.silu_and_mul.default
 FUSED_OPS: dict[QuantKey, OpOverload] = {
     kFp8StaticTensorSym: torch.ops._C.silu_and_mul_quant.default,  # noqa: E501
 }
-if current_platform.is_cuda() and hasattr(torch.ops._C,
-                                          "silu_and_mul_nvfp4_quant"):
+silu_and_mul_nvfp4_quant_supported = (current_platform.is_cuda() and hasattr(
+    torch.ops._C, "silu_and_mul_nvfp4_quant"))
+if silu_and_mul_nvfp4_quant_supported:
     FUSED_OPS[
         kNvfp4Quant] = torch.ops._C.silu_and_mul_nvfp4_quant.default  # noqa: E501
 
@@ -171,6 +172,7 @@ class ActivationQuantFusionPass(VllmInductorPass):
         pattern_silu_mul_fp8 = SiluMulFp8StaticQuantPattern()
         pattern_silu_mul_fp8.register(self.patterns)
 
+        if silu_and_mul_nvfp4_quant_supported:
             pattern_silu_mul_nvfp4 = SiluMulNvfp4QuantPattern()
             pattern_silu_mul_nvfp4.register(self.patterns)