Arm backend: Move import in DecomposePermuteForU55Pass (pytorch#19331)

Importing on top-level causes a dependency cycle


Signed-off-by: Adrian Lundell <adrian.lundell@arm.com>

Author: AdrianLundell

backends/arm/_passes/decompose_permute_for_u55_pass.py

@@ -14,7 +14,6 @@
 from executorch.backends.arm._passes.arm_pass import ArmPass
 from executorch.backends.arm._passes.rewrite_slice import RewriteSlicePass
 from executorch.backends.arm.arm_vela import vela_compile
-from executorch.backends.arm.ethosu.compile_spec import EthosUCompileSpec
 from executorch.backends.arm.tosa.mapping import map_dtype
 from executorch.backends.arm.tosa.specification import get_context_spec
 from executorch.exir.dialects._ops import ops as exir_ops
@@ -112,6 +111,9 @@ def _violates_exact_constraint(
         permutation and dtype to check wheter it is supported.
         """
 
+        # Lazy import to avoid circular dependency
+        from executorch.backends.arm.ethosu.compile_spec import EthosUCompileSpec
+
         if dtype not in (torch.int8, torch.bool, torch.int16):
             return True