Update

[ghstack-poisoned]

Author: mcr229

backends/xnnpack/third-party/xnnpack.buck.bzl

@@ -1110,6 +1110,7 @@ def define_xnnpack():
             "-DXNN_ENABLE_AVX512FP16=1",
             "-DXNN_ENABLE_AVXVNNIINT8=1",
             "-DXNN_ENABLE_AVX256VNNIGFNI=1",
+            "-DXNN_ENABLE_AVX256SKX=1",
         ],
         visibility = ["PUBLIC"],
         exported_deps = COMMON_XNNPACK_DEPS + [