Arm backend: Relax Qwen3 VL BF16 tolerance on Arm64 (#20450)

Increase the TOSA BF16 atol for the Qwen3 VL full vision-model test on
aarch64 only.

Signed-off-by: Zingo Andersen <Zingo.Andersen@arm.com>

Author: zingo

backends/arm/test/models/Qwen3_VL/test_qwen3_vl_model.py

@@ -246,15 +246,22 @@ def test_qwen3_vl_full_models_tosa_FP(test_case: Qwen3VLModelTestCase):
 def test_qwen3_vl_full_models_tosa_FP_bf16(test_case: Qwen3VLModelTestCase):
     model, inputs = test_case.model_cls.prepare_model_and_inputs()
     model, inputs = _to_bfloat16_model_and_floating_inputs(model, inputs)
+    # Slightly higher atol for TOSA BF16 on aarch64 (MLETORCH-2048: numeric mismatch)
+    atol = (
+        0.4
+        if common.is_aarch64_host()
+        and test_case.model_cls is LowerableVisionModelWrapper
+        else 0.1
+    )
     with torch.no_grad():
         pipeline = TosaPipelineFP[input_t](
             model,
             inputs,
             aten_op=[],
             exir_op=[],
             tosa_extensions=["bf16"],
-            atol=1e-1,
-            rtol=1e-1,
+            atol=atol,
+            rtol=0.1,
         )
         pipeline.run()