[V1] Enable multi-input by default (#15799)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

vllm/engine/arg_utils.py

@@ -671,13 +671,13 @@ class EngineArgs:
             type=nullable_kvs,
             default=EngineArgs.limit_mm_per_prompt,
             # The default value is given in
-            # MultiModalConfig.get_limit_per_prompt
+            # MultiModalConfig.get_default_limit_per_prompt
             help=('For each multimodal plugin, limit how many '
                   'input instances to allow for each prompt. '
                   'Expects a comma-separated list of items, '
                   'e.g.: `image=16,video=2` allows a maximum of 16 '
-                  'images and 2 videos per prompt. Defaults to 1 for '
-                  'each modality.'))
+                  'images and 2 videos per prompt. Defaults to '
+                  '1 (V0) or 999 (V1) for each modality.'))
         parser.add_argument(
             '--mm-processor-kwargs',
             default=None,