[Release Only] Bugfix/fix nxp separable conv test (#14800)

### Summary
Fix failing separable convolution test. 

The error is larger on the CI than on my PC.

Fixes #14709

### Test plan
N/A

Co-authored-by: Martin Pavella <[email protected]>

Author: pytorchbot

backends/nxp/tests/test_split_group_convolution.py

@@ -110,7 +110,7 @@ def test_split_group_convolution__2d(self, _, input_shape: list[int], group: int
         input_data = torch.randn(input_shape, dtype=torch.float32)
         out1 = original_module(input_data).detach().numpy()
         out2 = modified_module(input_data).detach().numpy()
-        assert np.allclose(out1, out2, atol=2.0e-7)
+        assert np.allclose(out1, out2, atol=2.0e-7, rtol=1.9e-4)
 
         # Make sure the graph can be correctly quantized and lowered to edge.
         ep = _quantize_and_lower_module(