[Bugfix][Hardware][CPU] Fix `mm_limits` initialization for CPU backend (#7735)

vllm/worker/cpu_model_runner.py

@@ -113,8 +113,10 @@ class CPUModelRunner(ModelRunnerBase[CPUModelInput]):
         )
 
         # Multi-modal data support
-        self.multi_modal_input_mapper = MULTIMODAL_REGISTRY \
+        self.mm_registry = MULTIMODAL_REGISTRY
+        self.multi_modal_input_mapper = self.mm_registry \
             .create_input_mapper(self.model_config)
+        self.mm_registry.init_mm_limits_per_prompt(self.model_config)
 
         # Lazy initialization.
         self.model: nn.Module  # Set after init_Model