Revert "fix cmake"

This reverts commit d9bcfb2d4ae31177aac85047c31edbf39b4b4e90.

Author: bigPYJ1151

cmake/cpu_extension.cmake

@@ -96,9 +96,14 @@ set(VLLM_EXT_SRC
     "csrc/cpu/utils.cpp"
     "csrc/cpu/layernorm.cpp"
     "csrc/cpu/pos_encoding.cpp"
-    "csrc/cpu/quant.cpp"
     "csrc/cpu/torch_bindings.cpp")
 
+if (AVX512_FOUND AND NOT AVX512_DISABLED)
+    set(VLLM_EXT_SRC
+        "csrc/cpu/quant.cpp"
+        ${VLLM_EXT_SRC})
+endif()
+
 #
 # Define extension targets
 #