[Hardware] add platform-specific request validation api (#16291)

Signed-off-by: Joe Runde <Joseph.Runde@ibm.com>

vllm/v1/engine/processor.py

@@ -141,11 +141,6 @@ class Processor:
         else:
             params.guided_decoding.backend = engine_level_backend
 
-        from vllm.platforms import current_platform
-        if not current_platform.supports_structured_output():
-            raise ValueError("Structured output is not supported on "
-                             f"{current_platform.device_name}.")
-
         # Request content validation
         if engine_level_backend.startswith("xgrammar"):
             # xgrammar with no fallback
@@ -187,6 +182,11 @@ class Processor:
         # TODO(woosuk): Support pooling models.
         # TODO(woosuk): Support encoder-decoder models.
 
+        from vllm.platforms import current_platform
+        current_platform.validate_request(
+            prompt=prompt,
+            params=params,
+        )
         self._validate_lora(lora_request)
         self._validate_params(params)
         if priority != 0: