[Intel][Triton] Support `round_int8` for Intel backend (#38825)

Signed-off-by: Mieszko Dziadowiec <mdziadowiec@habana.ai>
Signed-off-by: Lucas Wilkinson <lwilkins@redhat.com>
Signed-off-by: Stefano Castagnetta <scastagnetta@nvidia.com>
Co-authored-by: Lucas Wilkinson <LucasWilkinson@users.noreply.github.com>
Co-authored-by: Stefano Castagnetta <scastagnetta@nvidia.com>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Kunshang Ji <kunshang.ji@intel.com>

vllm/model_executor/layers/quantization/utils/int8_utils.py

@@ -88,6 +88,13 @@ if current_platform.is_rocm():
     def round_int8(x):
         return tl.extra.hip.libdevice.round(x).to(tl.int8)
 
+
+elif current_platform.is_xpu():
+
+    @triton.jit
+    def round_int8(x):
+        return tl.extra.intel.libdevice.round(x).to(tl.int8)
+
 else:
 
     @triton.jit