Reenable some mxfp tests for XPU

[HBN-MichalSzy]

Addresses #4062

• skips same as CUDA
• skip large block tests for PVC
• add num_warps=8 for empty kernels case

[anmyachev]

To avoid being tied to the GPU name.

      # check maximum shared memory
        if triton.runtime.driver.active.utils.get_device_properties(
                triton.runtime.driver.active.get_current_device())["max_shared_mem"] <= 196608:
            pytest.xfail("XPU: Not enough shared memory")

[HBN-MichalSzy]

done.

[whitneywhtsang]

This PR lowers the pass rate from 93.9% to 85.36%, IMO the pytest.skip added in this PR can be changed to pytest.xfail.

[HBN-MichalSzy]

@whitneywhtsang xfail is not an option at this point, as it will increate the total execution time to many hours. Where is this pass rate drawn from? Perhaps we can filter out those newly skipped matmul tests until the execution time is fixed?