Clear out Dynamo cache in between tests

Differential Revision: D66255174

Pull Request resolved: pytorch/executorch#6990

Author: anijain2305

backends/xnnpack/test/ops/linear.py

@@ -497,6 +497,7 @@ def _test_linear(
         which ares then transformed into aten.linear.default by the ConvertToLinear pass.
         """
         for i, _ in enumerate(in_sizes):
+            torch._dynamo.reset()
             in_size = int(in_sizes[i])
             input_size = int(input_sizes[i])
             output_size = int(output_sizes[i])