[Inductor] Skip test_nll_loss_backward for intel GPU. (#126157)

Skip this test case due to unaligned behavior to CUDA for Triton `mask_load`. We submitted issue #126173 to elaborate on the root cause. We intend to skip this case for XPU first as we need to take some time to fix the issue and have full validation to update the Triton commit pin for Intel GPU.

Pull Request resolved: #126157
Approved by: https://github.com/EikanWang, https://github.com/peterbell10, https://github.com/desertfire

test/inductor/test_torchinductor.py

@@ -6126,6 +6126,7 @@ def fn(a, b):
                 (a, b),
             )
 
+    @skipIfXpu
     def test_nll_loss_backward(self):
         def fn(a, b, c):
             return aten.nll_loss_backward(