[XNNPACK][QS8] torch.cat (#104800)

Differential Revision: [D47304143](https://our.internmc.facebook.com/intern/diff/D47304143/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/104800
Approved by: https://github.com/digantdesai
diff --git a/torch/ao/quantization/backend_config/executorch.py b/torch/ao/quantization/backend_config/executorch.py
index 9546914..8c721fa 100644
--- a/torch/ao/quantization/backend_config/executorch.py
+++ b/torch/ao/quantization/backend_config/executorch.py
@@ -416,6 +416,16 @@
         .set_observation_type(ObservationType.OUTPUT_SHARE_OBSERVER_WITH_INPUT)
         .set_dtype_configs(dtype_configs)
     )
+    cat_configs.append(
+        BackendPatternConfig(torch.concat)
+        .set_observation_type(ObservationType.OUTPUT_SHARE_OBSERVER_WITH_INPUT)
+        .set_dtype_configs(dtype_configs)
+    )
+    cat_configs.append(
+        BackendPatternConfig(torch.concatenate)
+        .set_observation_type(ObservationType.OUTPUT_SHARE_OBSERVER_WITH_INPUT)
+        .set_dtype_configs(dtype_configs)
+    )
     return cat_configs