[xpu][test][FlexAttention]Enable the test_GQA on Intel XPU (pytorch#166376)

Pull Request resolved: pytorch#166376
Approved by: https://github.com/drisspg, https://github.com/EikanWang

Author: liangan1

test/inductor/test_flex_attention.py

@@ -1477,7 +1477,6 @@ def mask_mod(b, h, q, kv):
     @dtypesIfXPU(*device_configs["xpu"].dtypes_fast)
     @common_utils.parametrize("score_mod", test_score_mods)
     @skip_on_rocm  # TODO: NaNs on ROCM
-    @skip_on_xpu  # TODO: NaNs on XPU like ROCM, need another PR to fix.
     def test_GQA(self, device, dtype: torch.dtype, score_mod: Callable):
         inputs = (
             score_mod,